public function calculate_shipping() {
		$this->shipping_methods = $this->needs_shipping() ? $this->get_chosen_shipping_methods( WC()->shipping()->calculate_shipping( $this->get_shipping_packages() ) ) : array();

		$shipping_taxes = wp_list_pluck( $this->shipping_methods, 'taxes' );
		$merged_taxes   = array();
		foreach ( $shipping_taxes as $taxes ) {
			foreach ( $taxes as $tax_id => $tax_amount ) {
				if ( ! isset( $merged_taxes[ $tax_id ] ) ) {
					$merged_taxes[ $tax_id ] = 0;
				}
				$merged_taxes[ $tax_id ] += $tax_amount;
			}
		}

		$this->set_shipping_total( array_sum( wp_list_pluck( $this->shipping_methods, 'cost' ) ) );
		$this->set_shipping_tax( array_sum( $merged_taxes ) );
		$this->set_shipping_taxes( $merged_taxes );

		return $this->shipping_methods;
	}