Seeing that this conversation is continuing, I will add another question. 

Is there any way to have a discount reflect in the Sales Tax Liability?

For example if Item's original price was $100, yet we discounted it by 10%, that means we only sold it for $90. 

However, when we calculate our quarterly sales tax liability - the missing $10 is not reflected in the total at all. Meaning, according to the report, we sold that item for $100 even though we only sold it for $90.

That was really the intent with my original question - how do I apply a discount to a specific item so the discount is reflected in our sales tax liability?