Can you mock up a dummy file and put in some stages of the percentages according to the number of services? If it's just something to draw information from a table, it won't be too bad, if it's just getting a percentage of a commission depending on the number of sales, that won't be hard either. But if you could put something to together with mock sales targets/percentages and then just mock up your results, I'm sure I can get it working for you.