Fired Over A Fake $10 Bill, No Previous Write Ups

Hey all. I'm so confused I'm not sure what to do or feel. I've been with this employer since August as a full time supervisor. I've had no write ups. This job has also known from the start that around now, I'd be leaving. I've been trying to get into contact with him since Christmas. 4/5 days in a row of me calling no answer. Texted him to call me, no answer. Showed up and was told health inspector was there and couldn't talk. I was trying to ask to stay on weekends.

I closed new years and opened new years day. After my shift, he came in and pulled me into the office. Showed me a termination letter saying that I'm fired, over a $10 bill being accepted on my drawer. I didn't sign it.

I have no prior write ups or formal warnings. The way it also works at this company is that you can't be logged into two different computers at once. If I have one cashier, and I'm needed on hotline, and there's a front and drive thru register, there needs to be two people logged in separately. Otherwise you have to painstakingly log out, walk to wherever and log in, take the order, probably log out and run back to drive. It's a mess. There's no proof that I am the one who took it, but it falls onto me regardless.

He kept lying saying there was an issue with uploading and that's why I wasn't put on the schedule yet. I live in Illinois and I know it's an at will state. I've done more in this company than I probably should've with helping and overtime.

Do I just move on, or is this worth trying to fight in court for wrongful termination? I'm so confused. Thank you.