Is it bad that I "top off" my tank not because I want a really genuinely super full tank, but because I'm lazy and am rounding it to the next dollar so it's easier for me to balance my checkbook?

And while some of the gas may be going up that thing, is all of it? Cause I know in my quest to have $27 instead of $26.43, I have overflowed many a time. >_>