Show product item cost including tax

If you’d like to display the product item cost with tax included, you can add the following code to Code Snippets or to the file functions.php of your store theme/child theme.

add_filter(
    'woocommerce_order_amount_item_subtotal',
    function( $subtotal, $order, $item, $inc_tax, $round ) {
        if ( ! empty( $item ) ) {
            $subtotal = ( (float) $item->get_subtotal() + (float) $item->get_subtotal_tax() ) / $item->get_quantity();
            $subtotal = $round ? \Automattic\WooCommerce\Utilities\NumberUtil::round( $subtotal, wc_get_price_decimals() ) : $subtotal;
            return $subtotal;
        }
        return $subtotal;
    },
    10,
    5
);