Thanks for following this thread, @Connie92123. At the moment, setting up a percentage charge for all customers who pay by credit card is currently unavailable in QuickBooks Online.

I'll do my best to keep up with your request and ensure our Development team gets your idea. 

As I mentioned by my peers above, you can also check out our blog page for any newly added features or updates in QuickBooks.

Feel free to comment below if you have any other questions. Wishing you and your business continued success.