Amount of reduction
(A) In general The amount determined under this paragraph with respect to any dollar limitation shall be the amount which bears the same ratio to such limitation as— (i) the excess of— (I) the taxpayer’s adjusted gross income for such taxable year, over (II) the applicable dollar amount, bears to (ii) $10,000 ($20,000 in the case of a joint return).
(B) No reduction below $200 until complete phase-out No dollar limitation shall be reduced below $200 under paragraph (1) unless (without regard to this subparagraph) such limitation is reduced to zero.
(C) Rounding Any amount determined under this paragraph which is not a multiple of $10 shall be rounded to the next lowest $10.