Snippet to Add Handling Fee based on number of UPS Packages.

functions.php

/**
 * Snippet to Add Handling Fee based on number of UPS Packages.
 * Created at : 02 Jan 2018
 * Updated at : 02 Jan 2018
 * PluginHive Plugins : https://www.pluginhive.com/plugins/
 * Gist Link : https://gist.github.com/varun-pluginhive/82552099b55a500c4844df65d3e48723
 */

// Get the number of ups packages and set in session
add_filter( 'ph_ups_generated_packages', function( $ups_packages ) {
	global $woocommerce;
	if( ! is_admin() )	$woocommerce->session->__set( 'ph_ups_packages_count', count($ups_packages) );
	return $ups_packages;
} );

// Add the Handling Fee
add_action( 'woocommerce_cart_calculate_fees', function() {
	$handling_fee_per_package = 3.18;						// Set Handling fee per Ups Package

	global $woocommerce;
	if ( is_admin() )
		return;
	$ups_package_count = $woocommerce->session->__get( 'ph_ups_packages_count' );
	if( empty($ups_package_count) )	$ups_package_count = 1;
	$fee = $handling_fee_per_package * $ups_package_count;
	$woocommerce->cart->add_fee( 'Handling Fee', $fee, true, 'standard' );
	}
);