How to round a number only up?

Question

PHP

There is an array of numbers, for example: 21749, 21751, you need to get 21750, 21800 i.e. round only up.

echo round(21749, -1); // 21750
echo round(21751, -2); // 21800

But what if there are many numbers? Do not set precision manually. did like this:

$numbers = array(21749, 21751,);

foreach ($numbers as $number) {
  $precision  = -1;
  do{
    $r = round($number, $precision);
    $precision += (-1);
  } while($r <  $number);
  echo ':' . $r . '<br/>';
}

Are there other ways to "feng shui"? Those. to round up without specifying the number of characters?

Answer 1

function up(num) {
  return Math.ceil(num/50)*50
}
up(21749); //21750
up(21750); //21750
up(21751); //21800

Answer 2

21749 should be rounded up to how many characters? You can get 21750, 21800, 22000, 30000, 100000, 1000000, ... How should the program determine where to stop?