I know this has me in the minority of PCF hosts, but I am always prepared to pay out to the quarter. I just feel presumptuous and unprepared if I don't. That said I would say 95% of players will round down and most winners will additionally tip a couple singles which is more than enough to keep me happy.
But the original post is about how "difficult" it is to pay exact change, and it really isn't. Just make sure you have a substantial quantity of singles and fives and you'll be fine. If you can keep $50 in small bills, I like having $3 in quarters, $22 in singles, and $25 in fives. And then I will usually include $20-$40 of fives and tens as part of my initial buy in. If we are playing buy ins over $100, then I will do my buy ins with 20s to make sure I can break any 100s that come into play.
Same. People usually just say to round them down, but if they don't they get their quarters.