How do you assign payments to a specific category?

[Firedrake]

The title of this thread has been edited from the original: how do you except payments to a specific category

We are using the POS on android and i've created items and linked to categories. The problem is when people swipe their card we want to be able to pick a category for the payment to go to; Building Fund, Tithe Offering, etc.  But it doesn't reall give an option, it says manual key in the amount, but doesn't allow you to pick a category.  Or if you start with the category it only gives you the option for quantity.  Any  help would be appreciated.  Thank you in advance. 

[VanKalkerFarms]

you need to choose an item for the donation and the item is what is linked to the category.  

Make the item building drive and add it to the building drive category and make the item tithe and add it to the tithe category.

so you would pick building drive item, enter $50.  and you can also pick the tithe item, enter $40.  total would be $90 charged to the card but $50 would be in the category building drive and $40 would be in tithe category.