Apply tax for Canada PMPro example.

pmpro-canada-tax.php

<?php

/** 
 * Apply 13% if a user selects 'Canada'.
 * Add this code below to your PMPro Customizations Plugin - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

// Set 13% tax value.
function customtax_pmpro_tax($tax, $values, $order) {  	
	$tax = round( (float)$values[price] * 0.13, 2 );		
	return $tax;
}

// Apply the tax on load and when returning from PayPal and loading 
function customtax_region_tax_check() {
	
	if ( ! function_exists( 'pmpro_start_session' ) ) {
		return;
	}
	
	// Start the session
	pmpro_start_session();
	
	// If bcountry is found in session and value is CANADA apply tax.
	if ( isset( $_SESSION['bcountry'] ) && $_SESSION['bcountry'] == 'CA' ) {
		add_filter( 'pmpro_tax', 'customtax_pmpro_tax', 10, 3 );
		return;
	}
	
	// If bcountry is found in session and value is CANADA apply tax.
	if ( isset( $_REQUEST['bcountry'] ) && $_REQUEST['bcountry'] == 'CA' ) {
		add_filter( 'pmpro_tax', 'customtax_pmpro_tax', 10, 3 );
		return;
	}

}
add_action( 'init', 'customtax_region_tax_check' );