/// <summary>
 /// Button event for Cancelling an order. Sets DataContext to a new instance.
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 void OnCompleteOrderButtonClicked(object sender, RoutedEventArgs e)
 {
     if (DataContext is UsersMoneyGivenModelView view)
     {
         view.TotalOwed = order.Total;
         receiptprinter.Print(order.Receipt(true, view.TotalValue, view.TotalOwed));
         double change = Math.Round(view.TotalValue - view.TotalOwed, 2);
         var    screen = new ChangeControl(change);
         this.Content = screen;
     }
 }
 /// <summary>
 /// Completes order and prints the receipt.
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void OnCompleteButton_Clicked(object sender, RoutedEventArgs e)
 {
     if (DataContext is CashRegisterModelView view)
     {
         if (total == owed)
         {
             receiptPrinter.Print(order.Receipt(false, 0, 0));
             var screen = new OrderControl();
             this.Content = screen;
         }
     }
 }