I am weird... I usually do something arbitrary.... like 6-8 over or 12-14 over. Never right on a value of 5 or 10. Even when crusing "the speed limit" I'm either 1-2 over or under.

I can't say it's really worked for me... I've been pulled over and gotten 3-4 tickets in the past 6 years or so.... but that's what I do anyway.