To setup a groupon, you can use the discounts video to setup your preferred discount method.
Once you setup the discount, make sure the item has 'Requires Serial' checked off in the item info options.
Requires - 3.15.54Q and above.
You can do a custom report to track the Groupon Campaign.
Office ⇒ Main Toolbar ⇒ Reporting ⇒ Pivot Reporting ⇒ Advanced Tab
Use this SQL Statement to setup your report:
SELECT DisplayTotal as TotalOfOrder,Serial,UnitPrice
FROM tblProductOrderDetails
WHERE ProductName='Input Your Groupon ProductName'
You can then open the report and get the results, the serial numbers. The total spend on the order, the serial number and the amount of the discount.