Add 20% tax to all membership checkouts

my_pmpro_vat.php

<?php
/**
 * Add 20% VAT tax to all membership checkouts.
 *
 * 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/
 */

/**
 * Set tax rate to 20%.
 */
function my_pmpro_tax_rate( $tax, $values, $order ) {

	$tax = round( (float) $values['price'] * 0.2, 2 );

	return $tax;
}
add_filter( 'pmpro_tax', 'my_pmpro_tax_rate', 10, 3 );

/**
 * Edit level cost text for non-free levels to include tax information.
 */
function my_pmpro_tax_level_cost_text( $cost, $level ) {
	if ( ! pmpro_isLevelFree( $level ) ) {
		$cost .= '20% VAT added at checkout.';
	}
	return $cost;
}
add_filter( 'pmpro_level_cost_text', 'my_pmpro_tax_level_cost_text', 10, 2 );

/**
 * Change the "Tax" line item label on orders to "VAT".
 */
function my_pmpro_get_price_parts_change_labels( $pmpro_price_parts, $pmpro_invoice ) {
	if ( ! empty( $pmpro_invoice->tax ) ) {
		$pmpro_price_parts['tax']['label'] = 'VAT';
	}
	return $pmpro_price_parts;
}
add_filter( 'pmpro_get_price_parts', 'my_pmpro_get_price_parts_change_labels', 10, 2 );