42 C.F.R. § 408.27
Rounding the monthly premium
Any monthly premium that is not a multiple of 10 cents is rounded to the nearest multiple of 10 cents, and any odd multiple of 5 cents is rounded to the next higher multiple of 10 cents.
Any monthly premium that is not a multiple of 10 cents is rounded to the nearest multiple of 10 cents, and any odd multiple of 5 cents is rounded to the next higher multiple of 10 cents.