Fix number_to_rounded for large precision

before:
  ActiveSupport::NumberHelper.number_to_rounded '3.14159', precision: 50
  => "3.14158999999999988261834005243144929409027099609375"
after:
  ActiveSupport::NumberHelper.number_to_rounded '3.14159', precision: 50
  => "3.14159000000000000000000000000000000000000000000000"