Transaction fees are 2% + $1. So when you add the recurring amount add enough to cover recurring amount sufficient to cover the payment AND fee.
If the payment is $300, then its x 2% = $6 + $1 = $7, then calculate the recurring fee estimate on $307 x 2% = $6.14 + $1 = $7.14 (you might round it up as well).
Any extra payment will go toward interest or principal.

If the payment is $300, then its x 2% = $6 + $1 = $7, then calculate the recurring fee estimate on $307 x 2% = $6.14 + $1 = $7.14 (you might round it up as well).
Any extra payment will go toward interest or principal.