The buses in Edinburgh are exact change only and when I first moved there I got really good at manipulating self checkouts to give me valuable 10p and 20p pieces to use for fares.
Then eventually I moved and needed to use the buses enough to justify getting a pass, so I did. But I had about £25 in change by that point, which I went and spent on a food shop. So I was just there for ages, putting small change in the machine. The people behind me didn’t look impressed.