I'm from Austria
we usually add up ~10% but to a round number, so it can be 7-8% or 12-13% whatever sounds nicer.
if something adds up to 17,50€ - we would pay 20€....but if it's 18,70€ - it's still 20€.
If the service was bad (wrong order, bad food) - no tip. (rarely)
Fast food places...