You are able to manually type in the barcodes on the app.
To do this:
1. click on new purchases
2. Select your store type then the store you purchased the item from
3. Click on the barcode icon and it should take you to item details.
4. Type in the barcode
5. Tap right arrow
6. It should take you to the Item Cart page
7. Click on the right arrow and it should take you to the "Check out" page and then click on Transmit.