I'll have a nervous breakdown if the TV or car stereo volume is on an odd number.
yeah, 5 is allowable tho. or when the volume is like a bottom line and top line, allways have to have full lines.
this is very bad because my tv on 10 is kinda soft, but on 12 it's like my ears are blown out. 
Had a roommate that was like this. Had multiple remotes, so I'd always turn it up by 1 whenever he "fixed" it.
Thankfully, I don't suffer from that particular compulsion. I do, however, feel that there is always a perfect setting for everything, and I'm always trying to find it. This is why you may find me microwaving something for, say, 4' 22"