Adds a handling fee to EDD purchases that go through PayPal Standard

gistfile1.php

<?php
/**
 * Plugin Name: Easy Digital Downloads - PayPal Handling Fee
 * Description: Adds a handling fee to EDD purchases that go through PayPal
 * Author: Pippin Williamson
 * Author URI: http://pippinsplugins.com
 * Contributors: mordauk
 * Version: 1.0
 */

function pw_edd_paypal_handling_fee( $args, $purchase_data ) {
	$args['handling'] = '10';
	return $args;
}
add_filter( 'edd_paypal_redirect_args', 'pw_edd_paypal_handling_fee', 10, 2 );