code: public static function CEILING($number, $significance = null)
      {
          $number = Functions::flattenSingleValue($number);
          $significance = Functions::flattenSingleValue($significance);
  
          if (($significance === null) &&
              (Functions::getCompatibilityMode() == Functions::COMPATIBILITY_GNUMERIC)) {
              $significance = $number / abs($number);
          }
  
          if ((is_numeric($number)) && (is_numeric($significance))) {
              if (($number == 0.0) || ($significance == 0.0)) {
                  return 0.0;
              } elseif (self::SIGN($number) == self::SIGN($significance)) {
                  return ceil($number / $significance) * $significance;
              }
  
              return Functions::NAN();
          }
  
          return Functions::VALUE();
      }
docs: CEILING.
  
  Returns number rounded up, away from zero, to the nearest multiple of significance.
  For example, if you want to avoid using pennies in your prices and your product is
  priced at $4.42, use the formula =CEILING(4.42,0.05) to round prices up to the
  nearest nickel.
  
  Excel Function:
  CEILING(number[,significance])
  
  @category Mathematical and Trigonometric Functions
  
  @param float $number the number you want to round
  @param float $significance the multiple to which you want to round
  
  @return float Rounded Number