Apply 10% tax (GST) if Billing Address is in Australia

my_pmpro_tax_agst.php

<?php 
/**
 * Apply 10% tax if Billing Address is in Australia
 *
 * Requires Billing Address fields on checkout page
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_pmpro_tax_agst( $tax, $values, $order ) {
	if ( isset( $values['billing_country'] ) && strtolower( $values['billing_country'] ) == 'au' ) {
		$tax = round( (float)$values['price'] * 0.1, 2 );		
	}
	return $tax;
}
add_filter( 'pmpro_tax', 'my_pmpro_tax_agst', 10, 3 );
 
function my_pmpro_level_cost_text_agst( $cost, $level ) {
	$cost .= ' Customers in Australia will be charged a 10% GST.';
	return $cost;
}
add_filter( 'pmpro_level_cost_text', 'my_pmpro_level_cost_text_agst', 10, 2 );