Hello Susan:

Doug's technique works very well for calculating the fee just like a tax.

The issue that Yogi has wrestled with is that he wants to see a separate ECO line following each item. For example:
1 - Sold 10 Desktop computers
2 - ECO fee for 10 Desktop computers
3 - Sold 5 Notebook computers
4 - ECO fee for 5 Notebook computers
etc.

Doug's approach will display a single line for the total ECO fee amount. For example:
1 - Sold 10 Desktop computers
2 - Sold 5 Notebook computers
3 - Total ECO fee
etc.

If you only need to see a single total, then Doug's recommendation will work perfectly.