Ahaha, I used to get asked this in Vancouver ALLLLLL the time a few years ago. They'd bring 260 and ask for a 10 back. I had to put it on my website that I did not keep cash on me or provide change. Eventually I just made my rate an ATM friendly number (280) so that the question stopped.
Once I had someone ask me if they could pay in loonies and toonies ($1 and $2 coins). I had no problem with this (as a one time thing) as I needed them to park at uni and I thought they'd be wrapped. He showed up with them in 2 grocery store bags. I did inform him in advance that the counting would be coming out of his time