How to allow users to buy multiple products at once?

I have an order from on jotform where there is a $3.00 processing fee. how can I make it that customers can place more that one order with one time credit card submission without having to complete one order then place an additional?

I'm not sure if I understood correctly. Do you want to allow users to buy multiple products at once? If so, you can add the Quantity Selector to your payment form.

Related Guide: How to Add Options to Payment Forms

I saw that you already did it on this form for some products.

If I did not understand correctly, please elaborate on your question and provide us a link of the form you are working on.