S.C. Code Ann. § 37-3-201
(2) With respect to a consumer loan, including a loan pursuant to open-end credit, a supervised lender may contract for and receive a loan finance charge as provided:
(3) This section does not limit or restrict the manner of calculating the finance charge, whether by way of add-on, discount, single annual percentage rate, or otherwise, so long as the rate of the finance charge does not exceed that permitted by this section.
If the loan is a precomputed consumer credit transaction:
(5) Subject to classifications and differentiations the lender may reasonably establish, he may make the same finance charge on all amounts financed within a specified range. A finance charge so made does not violate subsection (1) or (2) if: