I sincerely hope that someone can help me.

We use Zoho Books in order to create invoices and keep track of our item stock. So far, so good.

But we also have a cash register where also our services and products can be paid. 

I am now loking for a way to: 

a) Reflect the sales from the cash register in Zoho Books. I know that "sales without invoice" could do BUT:

b) I also need to let Zoho Books know which items have been sold via the register.

I need to do this so that I can have a single source of trhuth for both income AND sold items.

Any advise is highly appreciated!

Thanks,

Mark