Reports & Product-Only Sales Calculation

I ran a report on some test entries to see how the calculation was determined and this is what I found.

 

I have two (2) sales entries which the total sales record report displays as follows:

Order 1:  Order Total: $134.10, Tax: $0.00, Discounts Applied: (10% Off - $14.9, Free Shipping - $4.8)

 

Order 2: Order Total: $154.91, Tax: $11.81, Discounts Applied: (10% Off - $15.9, Free Shipping - $4.8)

 

At the bottom of the report the totals are: Totals: $289.01, Tax: $11.81, Shipping: $9.60, Product-Only Sales: $267.60 (total sales minus shipping, payment and other charges).

 

Here's what I don't understand:

1. As far as I can tell, each of the individual order totals already takes into account the discounts applied.

2. The sales total displayed at the bottom of the report is the sum of the two order totals (134.10 + 154.91) = $289.01.

3. The Product-Only sales total at the bottom of the report is the sum of the two orders minus tax, shipping, discounts, etc. ($289.01 - $11.81 - $9.60) = $267.60.

 

Here's where I get confused, to get the product-only sales total you take the total sales amount of $289.01 (which already has shipping subtracted from it) and subtract the tax of $11.81, and you get a total of $277.20; which is different than what PC calculates as the product-only sales total because PC is subtracting the shipping charges twice.

 

Please, can someone verify that this is truely what is happening, or at least let me know that my math is wrong.

 

I think that I have been itemizing my state sales tax information incorrectly if I just went by the numbers PC generates in this sales report.

 

Thanks in advance.