Supermarket Managment Files

Hi! I'm a young developer that tries to improve his programming skills. That´s the reason I accept any suggest of my code, that is a small project 
I developed for my cousin of 10 years old, who has a bar code reader and wanted to simulate a Supermarket. If you don´t mind please rate the project
and if you have time you can do this questionary(http://www.strawpoll.me/19676756). Thanks for your attention and for downloading the app.