Wikipedia has a pretty comprehensive explanation of how the Finnish system works, although we also have a few Finnish posters on here so they’d probably know best if any of them would like to chime in on the nuances. in summary: it would appear the absolute minimum fine for anything subject to day-fines is 6 euros, and the minimum for “speeding in traffic” appears to be 115 euros because there is a fixed petty-fine amount associated with that offense.