How do I use conditions on payments?

Hi,

It depends on what you would like to achieve, in general, you can't add conditional logic inside the payment setup, like dynamically changing the products, changing prices depending on input values, and the likes. BUT, we do have advance setup that you can use for special pricing, taxes on products, shipping and coupon code feature. To learn more about setting up an order form, you can check our guide here: http://www.jotform.com/help/165-Setting-Up-Your-First-Order-Form.

Another thing that you can try is creating all the product and prices using plain form fields and passing the form calculation value to the payment total field. Here are the guides that you can check for that: 

How to perform a calculation using the Form Calculation widget? 

How to pass form calculation to a Payment total field? 

I hope this helps.