Standard tipping is 20%, 15% for lukewarm/bad service, 10% is the service was terrible. Caveat: this is in an expensive area of the US.

Waiters are taxed at 15% tips regardless of the tips they actually make and make no net hourly wage (i.e. under minimum wage therefore it all goes to social security, etc.); between 25-40% of a waiter's tips go to pay the bartender, bussers, etc. (depending on the restaurant's policies).

10% tip means your waiter just paid for part of your meal. Carryout is a different story since they make over minimum wage.