Parking Legally (or at least trying to)

Around our law school there are various parking options. The school has two students lots, both of which cost $2 per day. There are other per day lots, $5 and up. Or you can contract with some of the garages around on a monthly basis. The cheapest by far are the parking meters next to and within few blocks of the school.
Since, we only have to pay to park until 6pm, it becomes quite economical for night students who arrive around 5pm. Rates are anywhere from $1.00 per hour down to 10¢ per hour if you don't mind walking a bit. I usually park in the 50¢ per hour spaces.
That said, I swear these meter maids are coming out of my trunk. As soon as the flag turns red, there they are with their little machines. They click away and deposit some green paper on my car. To me there ain't nothing lovely about Rita. Sorry, Paul.
Well, last night, I arrived at school at the usual time (around 5). Put money in the meter. Oh man, only 45¢. I scoured my car for one more nickel. Nothing but pennies! Okay, not to worry it's only 6 minutes. What are the odds that between 5:54 and 6:00 Rita will pop out of my trunk. Damned if she didn't. That familiar green envelope was waiting for me when I got to my car. $25.

This would not be so hard of pill to swallow, except for the fact that I should have parking ticket credit. The city owes me one free violation!
The week before school started, I was heading to my car ready to leave, and I caught Rita making her deposit on my windshield. I still had 21 minutes left on the meter! When, I pointed it out to her, she took it back not saying a word. Not trusting Rita and that demon machine, I made note of the date and waited. Sure enough, 3 weeks later I get a notice in the mail of my violation.
You know I could fight it, and probably win. But it would take at least two hours out of my day, for $25. I know there is a principle involved, but I can't justify it.
I would probably come out better parking in the student lots for $2 per day.