3. Subject to any adjustment which may be required pursuant to the Regulations, the amount of any payment to be made by a licensed supplier in respect of the levy in period y shall be calculated by applying to the aggregate amount (exclusive of value added tax and levy) charged (whether or not any bill or invoice has been delivered to a customer) by the supplier for leviable electricity supplied by him during the qualifying month the percentage figure Ry where Ry is the percentage figure ry given by the formula—
after it has been rounded to the nearest tenth of a per centum (any odd twentieth of a per centum being rounded upwards).