I think I've seen this at one time but don't remember how to do it. I'd like
to compute the following type of schedule

0-500 0 percent
500-4999 15 percent
5000-9999 13 percent
10000-19999 11 percent
20000 9 percent
This isn't a simple lookup. For example for 15000
0 on first 500
15% on 4999-500 plus
13% on 9999-5000 plus
11% on 15000-10000.
Thanks for any help