How to take profit percentage in pivot table

Use calculated field feature of pivot table.
1) Keep your cursor on C1
2) Under option menu select click on formula function then select Calculated field
3)Now in click in formula area. Open the bracket, click on sales amount, press minus sign now click on COST OF GOODS SOLD close the bracket, now use / sign and click on COST OF GOODS SOLD.
4) Format the column with % sign.

hope this will help you.