What percentage of your daily sales are OTC cash? I hope a great deal. I wonder how you monitor and control your cash flow; you should have a record of every sale and how the funds were handled.
Does the customer use a credit card?
Do they pay by check?
Was it a cash sale?
How is each transaction entered? Does the salesperson ring up each sale in a cash register? Was the customer provided with a receipt? There has to be a record showing how the money was handled.
My recommendation is that each salesperson working in your showroom should have a book of numbered invoices. Every sale, even if it is for a single cane tip, must be recorded. The original invoice is given to the customer.
The register should record all sales, whether OTC, charge account or cash! (I visited with a dealer who uses a cash box!). It has to be capable of printings receipts of all transactions in duplicate. Then, your record of every invoice or receipt, cash sale or other, can have a copy stapled to it.
Each evening, the books must be reviewed to be sure that every transaction has been recorded. If it was a credit card transaction, that is easy to follow. If paid by check, no problem. The number of the check must be shown on the invoice. If you were paid with cash, be sure that was recorded as such.
I realize that if you have a dishonest employee, this person will find a way to fleece you, but by putting in checks and balances, you remove the temptation.