WooCommerce - Hide price suffix when product is not taxable.

functions.php

<?php // Do not include this if already open!

/**
 * Code goes in theme functions.php.
 */
add_filter( 'woocommerce_get_price_suffix', 'custom_woocommerce_get_price_suffix', 10, 2 );

function custom_woocommerce_get_price_suffix( $price_display_suffix, $product ) {
  if ( ! $product->is_taxable() ) {
    return '';
  }
  return $price_display_suffix;
}