I am wanting to add a divider wall in my garage to separate a work space from the parking area. I got a great deal on a 10 foot wide by 7 foot tall roll-up door. I framed my basement when finishing it, but nothing this wide. All documentation I have found on header sizing refers to load-bearing walls. This one will be self-sufficient and attached to existing walls and the existing ceiling. Any advice on how large the header need to be and how many jack studs?
You don't need a header, except to provide a "space" for your new overhead door to roll-up into. A header is to hold something "up". This is non-bearing, so you could use studs to create the space down from the roof (or ceiling) for the roll-up door to roll-up into. The load that you need to resist is the horizontal force on the "wall" above the new door. I'd use a double 2x6 laid flat at the head of the opening. (The door is not supported by the "header" either.)
I'd use 2-2x4 "jack studs"...just for stiffness on each side of the opening. (Technically, I guess they're not "jack studs".)
Doubled 2x10s, either sandwiched or in a U configuration, and with a bottom plate to match the wall thickness (2x4 or 2x6). Even though it's not carrying a roof load, anything with less height is likely to sag.
If you wanted to go cheap you could use a single 2x10 and notch your pin studs down to the plate. It would still be stiff enough vertically, though it may want to bounce a bit more horizontally.