Somewhere I read (maybe other long-term residents can confirm this - Delph or Harry?) that you have a 3/10 chance you not paying your fine will be ignored.
I wouldn't risk it - the usual way is to go after the bank account, and if they can't find you, they can put an alert in the Schengen database. It's really not worth the hassle of triggering a 'hit' in the database over an unpaid fine.
But from what I've heard - they are exceptionally slow at processing unpaid fines. They get there, but it can be years afterwards. I think there was even one case recently in Poznan where they took 5 years to actually get round to sending a demand for money!
Can you go to jail for things like that?
Sure, it's an unpaid fine. Best bet is simply to transfer the money to them, along with as many details as possible.