as a general rule in bars if they ask for your money when they serve you at the bar, as in UK, i do not give a tip but if we are sat at a table and get served then i would but usually you are only expected to leave loose change, maybe just a euro.
in restaurants it is much the same as UK where somewhere around 10% is perfectably acceptable.

I hate the obsession with tipping, the places of work should be paying these people decent wages to start with!!

My rule would be to tip if you get above normal service

When they leave your change on a saucer, just take the 'big stuff' and leave the coppers - its no point cluttering your pockets with 5's and 10's..unless you got really good service with a meal etc.

Aye, those 5's and 10's are a pain!!! We used to save them up and give them to our rep when on holiday, as those guys aint paid too well and they do a good job

I generally only tip if the service is good, as I would in the UK.

Last week in Tenerife (last week seems like an eternity away now!), we had bad service in the Aberdeen Steak House (one of a chain). We purposley left the exact money on the tray, paying in the smallest change possible. Petty of what!

i only seem to tip if it comes to an odd number normally round it up to the nearest 5- or 10 eauros.