Interface Location
The Fee API located at: https://txprocess.uat.ipayoptions.com/soap/feeapi.php
The RawFeeAPI located at: https://txprocess.uat.ipayoptions.com/soap/rawfeeapi.php
It will only be accessible from your domain when data has been sent via HTTP POST towards it.
FeeAPI will give you the cart converted to the currency of the payment method.
FeeAPI and RawFeeAPI will both give you the list of payment methods and the fields. Fields section in the response will have the input requirement for sending the transaction to the gateway.