You don't think the 52 man wasn't doing a little provoking? Maybe trying to get her to sass him even? It's completely unnecessary to insult some kid over giving you the wrong change.
Remember, your right to swing your arm ends where my nose begins.
Or in this case your right to swing your belt/hurl nickels ends where her/his fanny/head begins.
I am not saying that she was right to do it, big over reaction, but it wasn't assault.