If I take a 19x9.5 +22 and have an 1/2 inch added to the back side of the wheel making it a 19x10 that would give me a 19x10 +34.5 right? Is my math and understanding correct?

 

No, on our cars with positive offset, the measurement is from the flange to the centerline of the wheel. So by adding .5" to the back of the wheel, you're only moving the centerline .25" (6mm), therefore the offset would be 28.

You'll see in the following wheel offset calculator that if you insert the numbers comparing a 9.5 +22 to a 10 +28, it will leave the outer part of the wheel in the same location, but the inner part will have moved inward 12mm, or your 1/2", but once again, only a 6mm change in offset.
http://www.1010tires.com/WheelOffsetCalculator.asp