I'm in the wrong

Yesterday I'm sitting in the office while Jennifer is working the register. While in the office I can watch the security cams and see what's going on. So Jennifer is working with a customer. The customer places her order and Jennifer gives the lady her change. Well the woman must of asked for something extra and Jennifer walked back to the other employee and talked to her about this. That's fine and everything, except Jennifer left the cash register drawer wide open. Once I noticed this I wanted to see how long she would leave it open. After a minute or so, I finally walk up to the register, shut it, and then ask Jennifer what was the problem that happened with the last customer. After her not knowing what the problem was I told her about how the register was wide open. Jennifer said isn't wasn't a big problem, and that if it was, I should of shut it myself faster. She turned the whole thing around on me saying it was my fault for this and that.