In the US, service charges are usually not included in the bill.  Waitresses and taxi cab drivers are usually tipped 15-20% of the bill.  Some people also tip barbers and hair stylists a dollar or two.  If you do not carry your own luggage, bellboys and porters receive $1.00 for each piece of luggage.  No tips are given to theater ushers, airline personnel, gas station attendants, or "baggers" in grocery stores.

University News
October 2, 2015
Visionary social entrepreneur Ben Simon will present “Waste Not, Want Not: How Food Recovery Can End Hunger in the 21st Century" at Drake University on Tuesday, October 13.