Admin Fee Code

/**
 * Snippet Name:	Add a percentage handling/admin fee to the order
 * Snippet Author:	ecommercehints.com
 */

add_action( 'woocommerce_cart_calculate_fees','ecommercehints_percentage_checkout_fee' );
function ecommercehints_percentage_checkout_fee() {
  global $woocommerce;

	if ( is_admin() && ! defined( 'DOING_AJAX' ) )
		return;

	$percentage = 0.03;// The percentage fee
	$surcharge = ( $woocommerce->cart->cart_contents_total + $woocommerce->cart->shipping_total ) * $percentage;
	$woocommerce->cart->add_fee( 'Admin Fee', $surcharge, true, '' ); // The order item label

}