They just raised the speed limit on rural interstate sections to 80 MPH here in Idaho. I did hear that the state police are enforcing it pretty strictly, too - the "5 MPH rule" doesn't apply any more.
When has it ever been a 5 MPH rule? I have been driving interstates for many many years and gone through speed traps and as long as I am not 10MPH or more over have never been stopped. In fact a NY State trooper (a friend of mine) once told me that that was the "unwritten" rule almost everywhere except maybe Mayberry RFD.