This seems silly to me, but it appears that any percentage type field used in a calculated field is treated as a number instead of a percentage.
A percentage field set at 20%
A currency Field set at $500
multiplied together = $10,000
Change the 20% to 0.20% and then it equals $100.
Maybe this is intentional, but I cant’ figure out why.
The best workaround for this right now is to include a constant in the formula (i.e., multiply the result by .01). We recognize that this is suboptimal behavior and we do plan on addressing it in the future.