How can I add on a 3% charge to every order?

Our client wants to pass on a 3% charge to every order, similar to tax. Please advise.

Thank you,

Michelle

You can add a sales tax to your form, here is a guide that will help you with that: How-to-Add-Tax-to-Your-Payment-Form

This way you can charge the 3% needed, you can charge it to all your products or only the products that you want. 

Please do let us know if you have any question.