WC_Order_Item_Tax::set_shipping_tax_total PHP Method

    public function set_shipping_tax_total($value)
    {
        $this->set_prop('shipping_tax_total', wc_format_decimal($value));
    }

 /**
  * Update tax lines for the order based on the line item taxes themselves.
  */
 public function update_taxes()
 {
     $cart_taxes = array();
     $shipping_taxes = array();
     foreach ($this->get_items(array('line_item', 'fee')) as $item_id => $item) {
         $taxes = $item->get_taxes();
         foreach ($taxes['total'] as $tax_rate_id => $tax) {
             $cart_taxes[$tax_rate_id] = isset($cart_taxes[$tax_rate_id]) ? $cart_taxes[$tax_rate_id] + $tax : $tax;
         }
     }
     foreach ($this->get_shipping_methods() as $item_id => $item) {
         $taxes = $item->get_taxes();
         foreach ($taxes['total'] as $tax_rate_id => $tax) {
             $shipping_taxes[$tax_rate_id] = isset($shipping_taxes[$tax_rate_id]) ? $shipping_taxes[$tax_rate_id] + $tax : $tax;
         }
     }
     // Remove old existing tax rows.
     $this->remove_order_items('tax');
     // Now merge to keep tax rows.
     foreach (array_keys($cart_taxes + $shipping_taxes) as $tax_rate_id) {
         $item = new WC_Order_Item_Tax();
         $item->set_rate($tax_rate_id);
         $item->set_tax_total(isset($cart_taxes[$tax_rate_id]) ? $cart_taxes[$tax_rate_id] : 0);
         $item->set_shipping_tax_total(isset($shipping_taxes[$tax_rate_id]) ? $shipping_taxes[$tax_rate_id] : 0);
         $this->add_item($item);
     }
     // Save tax totals
     $this->set_shipping_tax(WC_Tax::round(array_sum($shipping_taxes)));
     $this->set_cart_tax(WC_Tax::round(array_sum($cart_taxes)));
     $this->save();
 }