With Tappr you can add a photo to custom transactions at checkout. This is useful if you have yet to add an item to your product library. To add a photo to your checkout, follow these instructions.
If you've set up items previously you can access your product library by swiping from right to left on the main page of the app.
From there tap the photo icon (pictured below).
Then select Take Photo or Choose from Library and you're set (pictured below).