I never have that much money in my wallet, right now I have a five and a single. I usually keep the same sort of bills together, but other than that it's pretty haphazard, doesn't really matter if I lose track of how much i have in there.
I will arrange it in order of value, but I rarely have more than $20 on me at a time unless I know I will need cash for some reason. I was robbed at gunpoint ten years ago and lost a little over $50. I can see somebody using cash if they want to buy something they don't want to appear on their credit card statement for whatever reason. Also, one of the dry cleaning places I use gives you a 20% discount for paying in cash, so I'll use cash for them.