Sliding scale for Mark Up

[Larry Holmes]

How can I create a sliding scale for the B column(%) and then automatically have the correct markup entered into E5 (markup from scale+price of item)based on the scale and price in E3(price of item)??? Many Thanks couldn't download example.....

A B E
1 0-.25 100%
2 .26-1 80%
3 1.01-5 60% 8.5 Price of Item
4 5.01-10 35%
5 ?? Mark up based on scale and price of item