Electronic payment

Customers can also pay me via a payment terminal (Sumup). If a customer buys something from €20, for example, the transaction costs (in this case €0.36) are automatically deducted when the payment is made to my bank account. This means that €19.66 is deposited into my bank account. What is the best way to enter this? Should I just enter €19.66 under daily income and that’s it? Or should I enter €20 under daily receipts and then €0.36 under expenses? (For your information: I am self-employed in secondary occupation, a small business subject to tax exemption).