What do I put on a job application for reason for leaving if I was fired for disagreeing with the boss?

I worked at a convenience store/travel center. My boss stated that I "solicited" while on the clock...When in reality myself and a co-worker left the premises with a customer after my shift. As far as doing my job I always did. I even filled in for the manager on his days off doing his paperwork and such. I received unemployment since they decided it was a bogus reason for getting fired. It's been a year and now it has ran out so I am looking for a new job, but this is the only time I have ever been fired so I am embarred and unsure of how to go about explaining this on an application.