income for families with greater family incomes as described in clause (ii), to determine a copayment for a family receiving assistance under this section (or, for a family receiving part-time care, a reduced copayment that is the proportionate amount of the full copayment). (ii) Sliding fee scale A full copayment described in clause (i) shall be determined using a sliding fee scale that provides that, for a family with a family income— (I) of not more than 85 percent of State median income for a family of the same size, the family shall not pay a copayment, toward the cost of the child care involved for all eligible children in the family