Count the total of my overall sales in data report

I want to calculate the total of my overall sales in my datareport using visual basic 6.0 but I don't know how to code that.
This is an example of the display that appears in my datareport.
customer name product name quantity price total
John Doe soap 5 5.00USD 20.00USD
Allen Smith shampoo 2 7.00USD 14.00USD
Total Sales: ??????
How can I code the total sale in datareport using vb6.0?
