Can coupon codes be utilized?

Can coupon codes be utilized? Currently we ask: "do you have a coupon?" IF YES then the registrant enters an active code in a dialog box and the correct amount is deducted from the final amount.

Sure you can, depending on your chosen payment processor, the general way to add coupon codes can be found on the guide below:

https://www.jotform.com/help/233-How-to-Add-Coupon-Code-to-Payment-Forms