I have always understand "standard" to mean something is virtually always true.

In that sense, there seems to be much mis-information quoted here. For example, in my experience service charges are not standard in European restaurants or pubs. Some may include the charge when there are a large number of guests in one party. When I have seen this, it is usually explained in the menu. There may be exceptions.

Rounding up, as UK1 wrote, is indeed quite common, but I think the German expression for it (Trinkgeld) is probably more accurate than "tip." Alcoholic drinks in Germany (especially in pubs and especially in the countryside) are very low cost. And several guests rounding up their bills would probably give the waiter enough to have a beer or schnapps after work.