Since all the other threads are about should you or shouldn't you & usually get into a philosophical discussion, thought I'd post something I read in newspaper that was taken from Magellen's. It's a more specific guide by country.

REGIONAL TIPPING TIPS

Asia/the Pacific: Special care must be taken to ensure that your well-meaning gesture is not taken as insulting. If you are unsure, it is best not to tip. If possible, observe the locals and follow their lead.

Europe: Many hotels and restaurants add a service charge to the bill. In most cases, an additional tip is unnecessary. If no service charge is added to your bill, 10% is the general rule for restaurant service, and $1 per bag for a hotel porter.

Middle East/Africa: While your tip will not be seen as insulting, it may be unnecessary. Once again, the best bet is to do as the locals do.

Central/South America: Many hotels and restaurants add a service charge to the bill, and an additional tip is unnecessary. If not, 10% is the general rule for restaurant service, and the equivalent of $1 per bag for a porter.

FOREIGN TIPPING GUIDE - COUNTRY

This list is by country, and then waiter/waitress, porter, and taxi driver categories.

Argentina
W/W: 10%
P: $1
TD: Round up taxi fare or small tip

Australia
W/W: 10% in fine restaurants only
P: $2 per bag
TD: Round up

Austria
W/W: 5% plus service charge
P: $1 to $2 per bag
TD: Round up

Bahamas
W/W: 10%
P: $1 per bag
TD: 10% (15% actual per local FTer

Belgium
W/W: 10% if no service charge
P: $1 per bag
TD: Round up

Brazil
W/W: 10% to 15%
P: $1 per bag
TD: 10%

Brunei
W/W: None
P: None
TD: None

Canada
W/W: 15% ranges from 10%-20% per local FTers
P: $1 to $2 per bag
TD: 10%

Cayman Islands
W/W: 15% if no service charge
P: $1 per bag
TD: 10%

Chile
W/W: 10% in addition to service charge
P: $1 per bag
TD: None

China
W/W: 3% in major cities (according to local FTers; 0%)
P: $1 to $2 (according to local FTers, none)
TD: None

Colombia
W/W: 10%
P: 75 cents per bag
TD: None

Costa Rica
W/W: None
P: $1 per bag
TD: 10%

Czech Republic
W/W: 5% to 10%
P: $1 per bag
TD: Round up

Denmark
W/W: None
P: $1 per bag
TD: Round up

Ecuador
W/W: 10% if no service charge
P: 75 cents per bag
TD: None

Egypt
W/W: 5% to 10% plus service charge
P: $1 per bag
TD: Round up

Estonia
W/W: 10-15% for restaurants (in pubs toss spare change into big shared bowl for waitresses)
P: ?
TD: ?

Fiji
W/W: None
P: None
TD: Round up

Finland
W/W: None
P: None
TD: If you pay by credit card - none. If you pay with cash - none if you don't want to, but rounding up is acceptable to avoid hassling with coins.

France
W/W: 5% to 10%
P: $1 per bag
TD: Round up

Germany
W/W: 5% to 10% or round up plus euro or two per some FTers
P: $1 per bag
TD: Round up

Greece
W/W: 5% to 10% plus service charge
P: $1 per bag
TD: Round up

Hong Kong
W/W: 10% plus service charge if svg charge no need to add 10% per local FTer or round up
P: $1 per bag
TD: Round up

Hungary
W/W: 10% if no service charge
P: None
TD: Round up

India
W/W: 10% if no service charge
P: $1 per bag (according to local FTers 50cents/bag)
TD: Round up

Indonesia
W/W: 10%
P: 50 cents
TD: Round up

Ireland
W/W: 10% to 15%
P: $1 per bag
TD: Round up

Israel
W/W: 12% to 15% if no service charge
P: $1 per bag
TD: 12% to 15% (according to local FTers, tips included in fares; could tip but not 12-15%)

Italy
W/W: 10% plus service charge
P: $1 per bag
TD: Round up

Japan
W/W: None
P: None
TD: None

Malaysia
W/W: None
P: None
TD: None

Mexico
W/W: 10% to 15%
P: $1
TD: 50 cents

Morocco
W/W: Leave loose change
P: 50 cents per bag
TD: Round up

Netherlands
W/W: 5% to 10%
P: $1 per bag
TD: Round up

New Zealand
W/W: None
P: None
TD: None

Norway
W/W: 10% if no service charge
P: $1 per bag
TD: Round up

Oman
W/W: None
P: None
TD: None

Peru
W/W: Up to 10% for special service
P: 75cents per bag
TD: None

Philippines
W/W: 10%
P: 50 cents to $1 per bag
TD: Round up

Poland
W/W: 10%
P: $1 per bag
TD: Round up

Portugal
W/W: 10% to 15% if no service charge
P: $1 per bag
TD: Round up

Romania
W/W: Round up bill
P: $1 per bag
TD: Round up

Russia
W/W: 10% to 15%
P: $1 per bag
TD: Round up

Samoa
W/W: None
P: None
TD: None

Saudi Arabia
W/W: 10% to 15%
P: $1 to $2 per bag
TD: 10%

Singapore
W/W: None
P: None
TD: None

South Africa
W/W: 10% if no service charge
P: 50 cents
TD: 10%

South Korea
W/W: None
P: None
TD: None

Spain
W/W: 7% to 10% plus service charges
P: $1 per bag
TD: 10%

Sweden
W/W: 10% if no service charge
P: $1 per bag
TD: Round up

Switzerland
W/W: Round up
P: $1 per bag
TD: Round up

Taiwan
W/W: 10% if no service charge (none according to local FTer)
P: $1 per bag
TD: None

Tanzania
W/W: 10%
P: None
TD: None

Thailand
W/W: None see post # 32 in this thread for update by local FTer
P: None see post # 32 in this thread for update by local FTer
TD: None see post # 32 in this thread for update by local FTer

Turkey
W/W: Round up
P: $1 per bag
TD: Round up

United Arab Emirates
W/W: None
P: None
TD: None

United Kingdom
W/W: 10% if no service charge
P: $1 per bag
TD: 15% (according to local FTers 10% or round up to nearest pound)

USA
W/W: 15% to 20%
P: $1 to $2 per bag
TD: 10% to 15%

Venezula
W/W: 10%
P: 75 cents per bag
TD: 10%

Vietnam
W/W: None
P: None
TD: None