C# Point of Sale System - Touchscreen friendly

I'm looking for a C# Point of Sale System that will run on a touchscreen PC. The system should include source code files, and support multi-store installations, offline mode (when the internet gets interrupted but should be able to synchronize back once a connection is restored). A well designed attractive and intuitive user interface for the till operator must be implemented. Support for barcode scanning. Printer support Additional requirements : 1. Menus and action shortcut POS main till • Intuitive product layout • Search field for looking up product quickly • Normal size,(blue, white, black) and large buttons • Tap to add products to a bill 2. Discounts and promotion The system should allow admin to apply a basic discount to transition 3. Sales Prompts The system should allow the employee to trigger customer messages during transactions for certain products 4. Refunds The system should be built-in with the ability to perform refund with the admin’s permission Inventory management 1. Attributes, options, variants Variants is the best for our system 2. Stock alert The system should send a warning when the product is running low 3. Supplier integration Will do at a later stage 4. Barcode and product tracking The system should use the Universal Product Code (UPC) for barcode scanning Employee management 1. User accounts and logins The system should automatically log out 5 minutes if the computer is not used. 2. Admin account The system should allow more than one admin. 3. Employees permission The system should have a list of permission and they should be the granted by the admin 4. Timesheet and wages The system should integrate a timesheet feature to manage work shift and upcoming wages Reports, analytics and accounting The system should report end of day sales record that finalizes the trading day to the admin Location management 1. Location-based analytics The system should backend include location-based analytics