Ok...so what's your question?
ETA: If it was the customer's responsibility to pay your boss at the register, why would you think the customer was "testing" you?
hey guys, i was in charge of waiting tables not collecting the money. My boss is responsible for running the cash register.
Not sure what your question is. But I'm surprised this seems to bother you. Did your boss need to confront her or could you have done it? I would assume that is part of your job, unless you are not the one collecting the money. She may have just made an innocent mistake (I've done the same thing, thinking it was a different amount). But whether it was intentional or an accident, if you were collecting the money, you should have be the one to say something. That's part of being mature - handling "difficult" situations.
maybe it was atip?
She may have made an honest mistake. IMO if you are mature and calm you would have respectfully pointed out the error directly to her without having your boss confront her about it.
There are far better things to worry about in life. Dont sweat the small stuff. Water under the bridge. Move on with life.
maybe she couldn't read the bill and left what she thought the bill to be
So I waited on this elderly couple, I did not have an issue with them when they ordered their food. Until when the lady left $15 but the bill was $20. My boss confronted her and she apologized and paid the right amount. I`m not sure if she is testing me out because I`m new or she assumes that I do not know anything but I`m just a server. In my opinion, I`m more than a server, but a knowledgeable person, mature, calm, and plus I`m getting ready to graduate next year from college.