Please follow the steps below to round off Paisa balance in Sundry Debtors at the time of closing the books of accounts
Under chart of accounts >> Income a head called Round off is available-
Post invoices(Select income account "Round off") where advance has to be rounded off
Post Credit Note(Put Comment "Round off) where outstanding has to be rounded off
Note :-This is only a suggestion.For Audit related Accounting clarifications, please consult your auditor.