Add terms to Box Office Statement report

I'm sure all cinemas using Agile have terms for each film they show. Could the "Box Office Statement" report have two custom fields added to make our final statement more usable as-is? One would be for the guarantee payment and one for the percentage of gross. Standard terms are like $250 or 35%, whichever is more. So there would need to be a formula in there to subtract the guarantee from the gross and apply the % and show what is due (if more than $0).