Adding a processing fee for donations or fill in amount for registration type

We are looking to add a processing fee for our online gifts. I have found I can use "sell a product" and add a tax option, relabel processing fee and give users the option to add this with a conditional field in the form. This works for us.

However, for our online donations where people have the option to put whatever amount they want we have no ability to do something similar. 

Also, I wanted to give users the ability to make an additional donation as part of the registration and there was no ability to do this with a fill in amount. 

Is there anyway to either add a processing fee option to donations or to add a fill in amount on a registration.

Thank you.

In this case, you may consider calculating the total amount using regular fields, and then forwarding it to the payment tool.

1) Calculate the total amount.

- How to Perform Form Calculations

- How to Assign Calculation Value

2) Forward it to the payment tool.

- How to Pass a Calculation to a Payment Field

If you need any further assistance, please let us know.

I looked into this. This would work, however we want to give the user the option to give the money for the processing fee as opposed to it being automatic. 

This is why using the tax option in sell a product works, because i can have the tax amount conditional based on whether they say yes or no. So I have the standard tax set to 0%, then if they select yes it adjusts to 2.5% and if they select no it stays at 0%.

See what I did in this form, https://form.jotform.us/72027816806155. 

If i can have a write in amount with this set-up that would be awesome. Your suggestion works, but it does not give the user the ability to choose.

We can do this with custom calculations too.

Here is an example:

https://form.jotformpro.com/72176140206952

- Add prices using Calculation Values.

- Setup percentage using Calculation Values.

- Setup calculation formula: products * percentage.

The test form can be cloned.

This would work, however we do not want to have to give a list of suggested donations, we want people to be able to donate what ever amount they like. 

May I ask why you cannot just add another field wherein people can input the amount for donation?

Example:

test form: https://form.jotformpro.com/72186564078970

Let us know how we can be of further assistance.