Section 288A. ROUNDING OFF OF INCOME: The amount of total income computed in accordance with the foregoing provisions of this Act shall be rounded off to the nearest multiple of ten rupees and for this purpose any part of a rupee consisting of paise shall be ignored and thereafter if such amount is not a multiple of ten, then, if the last figure in that amount is five or more, the amount shall be increased to the next higher amount which is a multiple of ten and if the last figure is less than five, the amount shall be reduced to the next lower amount which is a multiple of ten; and the amount so rounded off shall be deemed to be the total income of the assessee for the purposes of this Act.
Section 288B. ROUNDING OFF OF TAX, ETC.: The amount of tax (including tax deductible at source or payable in advance), interest, penalty, fine or any other sum payable, and the amount of refund due, under the provisions of this Act shall be rounded off to the nearest rupee and, for this purpose, where such amount contains a part of a rupee consisting of paise, then, if such part is fifty paise or more, it shall be increased to one rupee and if such part is less than fifty paise, it shall be ignored.
So it seems that in my case, a tax of 45984.50 should be rounded off to 45985, while an income of the same amout should be rounded off to 45990.