h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

... don't tip. Ever. You don't have to, people will generally be nice to you as long as you don't treat them like your personal slave. Service is almost always included, as is the sales tax, so the price you see is the price you get.
The only exceptions are:
- exceptionally good service
- if the menu says 'Service not Included' (VERY RARE)
- telling the taxi driver to keep the change (so he doesn't have to fumble around for 35 cents)

I think it's actually illegal for a casino croupier to accept a tip in New Zealand!
Please, any Americans out there, if you ever come to New Zealand DON'T TIP, or else in a few years we'll all have to do it.

Conversely, New Zealanders (and Australians too) are notoriously bad tippers, and consequently get bad service sometimes in other countries. No wonder we tend to lose our accents quite quickly...