not many places like that will take a hundred, the most common of counterfeited bills.
$20 bills are the most common, since most people don't think to check them with a marker.
But to the OP, next time you are at the bank, just stash an extra $20 bill in the fold behind your credit cards. I usually do that just to make sure I always have some spare cash in case of an emergency.
But as others said, you should have had a debit/credit card with you. So you can always fall back to that.