I just looked at one of my square statements and I paid €1.06 on €48.80, which works out at 2.2%. The €1.06 has a little note --> Includes Square processing fees, third-party fees and VAT on fees. There were no other deductions etc, just those 2 numbers on the statement...
Others have mentioned sumup. I used it for ages but eventually couldn't trust it to work reliably. So I moved to Square and it works all the time. There's pennies in the different commission rates between the two but one works 100% of the time and one doesn't!