(3)On the amount of the bill remaining unpaid after thirty days of presentation of the bill under section 241, simple interest at the rate of twelve per cent for delay up to one month and at the rate of eighteen per cent for delay in excess of one month, shall be payable for the period commencing on the first day of the month following that in which the bill is presented and ending with month preceding the month, in which payment is made.Explanation. - In calculating the interest payable under this sub-section a fraction of a rupee in the amount of the bill on which the interest is to be calculated shall be rounded off to the nearest rupee, fifty paise being treated as rupee one.
