Ah... Then then they are not really part of the Credit Card/Bank daily Sales.
How do you record the sales now? Is it actually entered into your POS system or just a ledger or some sort of basic receipt pad to keep track of the purchases? If not part of the POS then the simplest way to deal with the purchase might be to just create an Invoice.
I'd probably just create one Invoice per month (or period between payments) and just keep adding to it. So if Ms Smith come in and buy something today you would open a new Invoice in QBs with either a one line entry or full details, whatever you want to do. Ms Smith comes in tomorrow and you open the same Invoice and add the new item(s). Next week Ms Smith comes in and want to pay, so you apply my payment against that Invoice. (Doesn't matter if I use a CC or Cash, you just apply the payment accordingly.) Next time Ms Smith comes in you create a new Invoice. Also you can print out the invoice when they pay to give give them a record of what they paid for that day.
Other option would be to create a new Invoice each time I buy something, then again just pay them all off when I come in to pay. This might be useful if multiple people are making the entries into QBs and you what to separate the people in case there are questions/disputes.
Notes: If you don't usually Invoice people and accept Cash payments, when you process the the payment will go into the Undeposited Funds Acct by default (you can change this, but no need to). The money will sit there until you go to Banking; Make a Deposit and actually record the deposit into your Bank Account, Cash Account or wherever you want to move it to.
Advantage is that if you do put it in a Bank Acct, the dates of the deposit actually match when you do it. So if you have a lot of deposits, when you go to Reconcile the date will actually match the deposit date vs. the customer's payment date.