Generating a sales report that shows actual sales figures versus undercounted sales figures.

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I have one customer that gets a discounted rate on the retail price of our services.  When I generate a sales report through the general ledger reporting option, the sales report shows the undercounted price instead of the actual invoiced amount.  Does anyone know how to generate a report that shows the actual invoiced amounts?   Thanks to anyone that can send me in the right direction.  John