Hi Steve,
Sorry, what I gave you was the pre-discount value for an item entry. Here is how to display what you're looking for. This will put the pre-discount amount right above the discounted subtotal on the out-of-the-box 40 column receipt. The 3rd line in this xml is the discounted subtotal that already exists (I've only added the words "(Post-Discount)" to the label). So you actually don't have to copy that 3rd line. You can search the XML for the 3rd line, and when you find it, paste the first two lines in my XML here above it.
I would recommend saving this receipt as a different file than the original out of the box 40-column receipt to keep the original untainted. Whether or not you do that, though, your next step will be to go to Store Operations Manager, Database > Registers > Receipt formats and open the properties of the 40-column receipt format. Click the lookup glass next to "Sales" and choose the XML file you just modified and saved. You will then have to restart POS at each register before that register will use the new format.
Transaction.SubTotal + Transaction.DiscountPurchased "Sub Total (Pre-Discount) |" PreDiscountSubTotal "Sub Total (Post-Discount) |" Transaction.SubTotal