When she said "don't worry about it" I would have said Oh!"I won't (big smile) and if you weren't so rough then maybe you wouldn't have dropped the change." (Optional)" Oh btw keep your hostile attitude in check and get some self-respect."
If this girl was rude once or twice I wouldn't really care but she sounds like she is Nasty and Miserable and people who are those two things should not work with the public. I would speak to the Manager and if he doesn't want to loose your business he should deal with this employee, and if he didn't I would go up the ladder to his boss, because I wouldn't want to go into a place every day and have to deal with that kind of treatment.