Into your table with data, add a column (may be hidden) , where depending on sales and GP % the bonus group number (values 1, 2, 3 or 4) for every row is calculated.
The bonus will be calculated as
Code:
=CHOOSE(BonusGroupNumber, Bonus1, Bonus2, Bonus3, Bonus4)
where Bonus# are numeric values for different bonuses like 0.01, 0.03, etc.