Today I took the 2nd test in my Probability Theory class. I was allotted 50 minutes, and when 50 minutes hit I wasn't done. Sure, I could have taken another 5 minutes, tops, and finished it, but I had to sign that I played by the rules and that 5 minutes isn't worth as much as my integrity. I stopped mid-problem and wrote "out of time" and turned my test in to my proctor.
I'm hoping for some "max partial credit".
Update, 11/3/13: I got 97%. I lost 3 points on the problem I didn't finish.