"A tip on tipping" United States of America Local Custom Tip by melosh

Tipping is voluntary but is expected in certain situations.
The idea is that a tip is a reward for personal service. It is also felt by many that it is a justified supplement for low paid workers.
When you should or should not tip can depend on the place, time and people involved.
Do not tip government officials, police officers or good samaritans. Sales people or managers including workers at fast food restaurants do not expect to be tipped. Some tipping of taxi drivers occurs expecially if special service is provided, but more commonly people just round off to next highest nearest dollar. In sit down restaurants with waiters or waitresses tipping generally ranges between 12 and 20% of the food bill. You need not tip on the tax. These workers are paid little salary and they survive on their tips. Usually there is a sharing mechanism so that the tips are shared with all the staff.
The amount you tip should reflect the service received and the place where you received the service. In general higher percentage tips are expected in bigger cities and fancier restaurants.
Rarely you may see a "service charge" added to your bill in the European style. Subtract this amount from your tip. Also a fixed 15% tip may be added to the bills for large groups. Again whether you add more depends on what you feel about the service. If the food is not very good and the service poor, tip little if anything unless you feel that the servers were sympathetic and not responsible for the problems.
Remember, tipping is optional. Do not be intimidated by rude taxi drivers! (See taxi tip under transportation.)