(d)the form of any notice of demand under this Act;(dd)[ the procedure to be followed in calculating interest payable by assessees or interest payable by the Government to assessees under any provision of this Act, including the rounding off of the period for which such interest is to be calculated in cases where such period includes a fraction of a month, and specifying the circumstances in which and the extent to which petty amounts of interest payable by assessees may be ignored;] [ Inserted by Act 42 of 1970, Section 66 (w.e.f. 1.4.1971).]