How do I add a donate button in addition to a registration fee, etc?

We are a non-profit youth basketball league and would like to add an option for additional donations. This would be an any amount aded to the registration fee that they are submitting. I would like if to add to the total amount.

Example:

$70  Registration Fee
$20  Uniform
$__  Donation

Total:_____

You can use a custom payment form with calculations. Then, pass the calculation amount to the Payment tool.

User guide: https://www.jotform.com/help/275-How-to-Pass-a-Calculation-to-a-Payment-Field

You can test my demo form https://www.jotformpro.com/form/62938394923974

Let us know how it goes.