Tipping

Tipping for good service is more common in the USA than in the UK, but there's surprisingly little consensus about when and how much to tip.
You should probably tip:

• In restaurants.  Really.  On at least one occasion, a restaurant called the police, and they came. 15% minimum. Be careful, as they might automatically add a tip to a large party (but you might still consider throwing a couple more dollars in there.)
• Taxi drivers.  15% - sometimes this is automatic (e.g. if you pay in advance).
• The postman is allowed to keep a tip of up to $20 at Christmas.

You should probably not tip:

• Take out food.  Unless they did something really special.
• Gas station attendants.  In some states there's always an attendant.  In others, you have the choice of self-service or full-serve.  The full-serve will cost you more (but they'll clean your windscreen and check your tyres and oil).