I understand how important it is to automatically add credit card processing fee to an invoice, @mkt2006.

Currently, this feature is not available. And since it is a helpful feature, I recommend you submit a feedback. This way, Product Developers can consider adding it in the future updates. 

Here's how:

1. Go to the Gear found in the upper-right corner.
2. Select Feedback under Profile.
3. Share your feedback.
4. Click Next to submit.

You can track the status of your request in this link: QuickBooks Online Customer Feedback.

For more details about handling credit card payments, check out these references:

• Common terms to process credit cards for Intuit Payments
• Choose where to record payments and processing fees for QuickBooks Payments

Feel free to comment below if you have additional questions about managing your invoices. Have a great day!