я чёто сделал

AutoService/ViewModels/ReceiptWindowVM.cs

@@ -1,5 +1,6 @@
 using AutoService.Models;
 using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
@@ -42,6 +43,11 @@ namespace AutoService.ViewModels
 
             TotalPrice = sumPrice * (1-discount);
 
+        }
+        [RelayCommand]
+        public void ProceedTransaction()
+        {
+
         }
     }
 }

AutoService/Views/ReceiptWindow.axaml

@@ -28,6 +28,6 @@
 			<TextBlock Text="Итого к оплате: "/>
 			<TextBlock Text="{Binding TotalPrice}"/>
         </StackPanel>
-
+        <Button Content="Подтвердить!" Command="{Binding ProceedTransactionCommand}"/>
     </StackPanel>
 </Window>