private void AddButton_click(object sender, RoutedEventArgs e)
        {
            string titl     = itemNameBox.Text;
            int    quantuty = int.Parse(quantityBox.Text);
            string type     = typeBox.Text;
            double price    = double.Parse(priceBox.Text);

            Item item = new Item(new Random().Next(), Title, quantuty, price, type);

            calculator.addItem(item);
            double total = calculator.getTotal();

            totalLebel.Content = String.Format("Rp. {0}", total);
            listBox.Items.Refresh();
        }
        private void AddButton_Click(object sender, RoutedEventArgs e)
        {
            string title    = ItemNameBox.Text;
            int    quantity = int.Parse(QuantityBox.Text);
            string type     = TypeBox.Text;
            double price    = double.Parse(PriceBox.Text);



            Item item = new Item(new Random().Next(), title, quantity, price, price, type);

            Calculator.addItem(item);
            double total = Calculator.getTotal();

            TotalLabel.Content = string.Format("Rp. {0}", total);

            Listbox.Items.Refresh();
        }