I did another test with the rev1 prototype, this time only measuring voltage, and bringing it all the way to the maximum voltage of 60V. Again I am doing calibration and comparison to my Fluke 101 Multimeter. This has a problem as the Fluke 101 does not have more digits than this multimeter, however, I am ignoring this for now. I was able to stay under 1% error for all measurements, and I think this could be improved with a better calibration procedure. Here are the results:

Voltage(V), Error(%)
0.989, 0.0
4.982, 0.71
9.97, 0.76
14.96, 0.81
19.95, 0.86
24.94, 0.85
29.94, 0.88
34.99, 0.86
40.03, 0.83
44.9, 0.81
49.89, 0.85
54.84, 0.9
59.8, 0.71