Elias here with Shopify Support. Thank you for reaching out.
I understand you're looking to add the transaction fees for credit card purchases to the order's total. While this isn't possible by default, as the transaction fees are charged to the merchant by the credit card companies. However, you can consider marking up your products by the same percentage as your fees. This way, customers aren't seeing the additional fees on their order, which should also be a better customer experience for them as well.
Alternatively, there's also a third-party app, called Order & Product Fees. Based on the description on their app's page, Order & Product Fees can add fees or additional options to your product or cart page. If you need any assistance with this app, the app developer are always available to help. To get in touch with the developer, you can use the contact information found in the Support section of their app's page.
I hope this gives you a couple of options to explore. If you have any other questions on this topic, don't hesitate to let me know!