All of you saying it's the employees' right to close the store early are displaying some pretty piss-poor work ethic.
I've worked retail before so I understand the desire to say, "**** it, let's go" but if you're not willing to work the hours you're supposed to, DON'T work there. Go find a job that lets you get off at 8:53pm or earlier.
About boycotting Autozone over this, I think that's going too far. Complain to their HQ, yes. Boycott, nah. But if you don't ever go back to that same store again, I wouldn't blame you. I'd be pissed too if I drove 20min to go somewhere that should be open just to have to turn right back around.