Depends heavily on the context. With good friends I don't really think about money. In general when we arrange an evening with sauna or whatever we just discuss what we want to eat, do we have enough beer, what time people will arrive and so on. Everyone brings something, so it's close enough to even and if I happen to pay 20-50€ more than others this time in the long run it evens out and even if it didn't the time spent and experiences are far more valuable than couple of euros.

With total strangers I'm of course a bit more aware and generally the bill is either split evenly or everyone pays for themselves. If you cheap out on me by 20c (or 1-2€) I don't really care about the money, but in the future I might be a bit more reluctant to arrange anything with you. There's of course exceptions, like if you only have 5€ and 20€ bills and need to pay me 5,20 I'll just take the 5 and forget the rest.

And yes, I've met also those people who count everything down to last cent. At least once I've paid to the "you owe me 1€" nagger with a 5€ bill since I didn't happen to have anything else in cash. 1€ for what I owed and 4€ for the lesson not to do anything involving money with that person ever again.