alt Hacker NewsIt really depends on the amount. In Belgium for instance there would be no tipping, but rounding up or adding one or two spare coins of change you still have on you in case the service was excellent.
It is like any job where people get a bonus because they have gone above and beyond.
Why can't the employer give that bonus? In non-service jobs employees don't get tips for going above and beyond; they get raises or bonuses.