This is wrong. Taxi drivers do not need tips. When we were there none asked for it and didn't seem upset that we didn't give one. I gave a $2 tip to the shuttle driver who took us from our hotel to the airport on our last day there and he was very excited by it. OTOH, he did take the fastest route possible even going by some local roads to avoid the traffic he knew was happening, so we were happy.

For waiters, there's a 10% service charge included. We often rounded up a bit when paying (cash almost everywhere) but its not required. OTOH, when your lunch costs $2/person, we had no problems leaving a dollar extra.