public function get_total_tax_refunded( $order ) {
		global $wpdb;

		$total = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT SUM( order_itemmeta.meta_value )
				FROM {$wpdb->prefix}woocommerce_order_itemmeta AS order_itemmeta
				INNER JOIN $wpdb->posts AS posts ON ( posts.post_type = 'shop_order_refund' AND posts.post_parent = %d )
				INNER JOIN {$wpdb->prefix}woocommerce_order_items AS order_items ON ( order_items.order_id = posts.ID AND order_items.order_item_type = 'tax' )
				WHERE order_itemmeta.order_item_id = order_items.order_item_id
				AND order_itemmeta.meta_key IN ('tax_amount', 'shipping_tax_amount')",
				$order->get_id()
			)
		);

		return abs( $total );
	}