Not enough detail here to give a reasonable answer.
Can you post an example of your requirements?
Maybe something like =LOOKUP(A1,{0,10000,20000,30000},{0,0.01,0.015,0.02})*A1
Where <10000 give no bonus, 10000-19999 gives 10%, 20000-29999 gives 15%
Anything over 30000 gives 20%
Gord Dibben MS Excel MVP