=FLOOR(A1,LOOKUP(A1,{0,20000,50000},{100,500,1000} ))

HTH
Jason
Atlanta, GA

-----Original Message-----
In my business, we have to round numbers DOWN, not to
the closest 1000, for
values over 50,000. From 20-50,000, we have to round
DOWN to the 500. Under
20000, we have to round DOWN to 100. I can't figure it
out.
.