+ #&{ $opt{post_fee_callback} }( \$amount ) if $opt{post_fee_callback};
+
+ $surcharge_percentage = $opt{'surcharge_percentage'}/100 if $opt{'surcharge_percentage'} > 0;
+ $surcharge_flatfee = $opt{'surcharge_flatfee'} if $opt{'surcharge_flatfee'} > 0;
+ $surcharge = $amount * $surcharge_percentage if $surcharge_percentage > 0;
+ $surcharge += $surcharge_flatfee if $surcharge_flatfee > 0;
+
+ $amount += $surcharge;