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 R_y where R_y is the percentage figure r_y given by the formula—

ry=Ky+Dy"Xy"×100

after it has been rounded to the nearest tenth of a per centum (any odd twentieth of a per centum being rounded upwards).