Let's say that Qty Sold is in B2 and down. In C2:
=IF(B2<3, 0, IF(B2<6, 10, 25))
or
=10*(B2>=3)+15*(B2>=6)
The formula can be filled down.
Let's say that Qty Sold is in B2 and down. In C2:
=IF(B2<3, 0, IF(B2<6, 10, 25))
or
=10*(B2>=3)+15*(B2>=6)
The formula can be filled down.