It all depends on your data needs. Provided you don't need to track the sales on a per-customer basis and aren't tracking data on those customers (names, order history, etc,) then aggregating into one or a few cash sales per day make sense. I've worked with a few restaurants that do this, however retail and grocery have returns co consider whereas restaurants do not, so I assume you'd need to do the same with Cash Refunds as well. Basically, combining the cash sales as much as you can to a point that still allows for useful, reportable data for you would be your best bet.