a seprate right to allow a person to issue cedit note must be

a seprate right to allow a person to issue cedit note must be added in ROLE (POS MANAGEMENT) .

This is NATIONAL SUPER MARKET, JAIPUR

At the time of billing, if a customer purchased a item of rs.100 and he paid 100 and if the cashier entered Rs. 200 in any MOP other than the cash then a option of "issue credit note and save" for Rs. 100 will be highlighted automatically and later that cashier can adjust that credit note with any other bill.

now the issue are -

we don't want our cashier to issue any kind of credit note because that may result as a fraud in near future and in the user and role managemet, we don't have any such right to prevent him from making a credit note.
amount in any MOP (other than cash) should not exceed the bill (invoice) amount.