If there is only one cash-in ticket (or one cash-in entry, if you don't use paper tickets), you would not list multiple transactions. As noted, aggregate transactions would also not be selected.
As for whether I'd record the receipt of the $50, I could go either way. I'd definitely do so (listing it as a currency exchange) if my cash log shows the receipt of the full amount and a pay-out of the $50 "change," but only because it avoids having to respond to auditor/examiner questions about the $50 difference. But if the only cash log entry resulting from the transaction is the $12,850 purchase price, I'd probably go the other way and ignore the fact that the teller held the extra $50 for 5 seconds.
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John S. Burnett
BankersOnline.com
Fighting for Compliance since 1976
Bankers' Threads User #8