The payment processing fee is paid by the customer and is included in each payment. It is a share of the whole payment: 3.54% of the payment in Australia, the United States and Canada, and 2.36% in India (the payment provider's fee plus the GST on that fee).
Before you press Pay, the Billing page shows the total for the months you chose, with the processing fee and any GST it includes. Nothing else is ever added.