Hello, kqbrosis.foods. 

Thank you for getting back to us here in the Community. In QuickBooks, there are various reports you can pull up. One of the reports you can pull up to show the total discount given to a product is the Sales by Product/Service Detail report. 

Here's how:

1. Go to Reports from the left menu.
2. Enter Sales by Product/Service Detail in the search bar.
3. At the upper-right click Customize. 
4. Change the Report period.
5. Click the Filter, under Product/Service drop-down and select Discount.
6. Select Run Report.  

I've also added an article that can help you customize and memorize your report in QuickBooks Online. 

Please don’t hesitate to comment below if you need further assistance. I’ll be back to you. Take care.