5mm does not warrant replacement. When they get to about 2-3mm you should think about getting them done. New pads are usually about 8-10mm. As for the rears, I could not comment as you did not supply any measurements of pad thickness. Unless the vehicle has had brake work already done to it prior to this, needing to do the rears before the fronts is abnormal. The front's do 70% of the braking.
Techs will usually try and sell rotor resurfacing over new rotors as they make more time on it. Depending on the vehicle it could be about the same price to get new rotors. But you only need new rotors in a case of when the rotors are beyond their minimum machining spec, have been warped or excessive hot spots. Sometimes you can get away with putting new pads in, but at the minimum have them machined to remove imperfections that could effect the wear of the pads.
So I will say for sure, that unless you have a pulsating pedal when braking, you DO NOT need the fronts done. As for the rears, I do not have enough information to make an educated assessment.