As dmx said, #10 Cu would be the bare minimum.
That 5% is the maximum VD recommended for the entire circuit, feeder and branch circuit combined. It's 3% recommended maximum for just the feeder.
I would recommend at least #8 or #6 Cu. It would give you a little more wiggle room should you need to add another load or change to a different motor.
The larger wire may also help as the motors age, and take more current to start up.