Function for rounding any number to the value of a specified base. e.g. If using base 2 (1,2,4,8,16,32,64,128....) the 17 would round up to 32.

roundToBaseFunction.php

<?php

function roundToBase($value, $base = 2)
{
  $result = log($value, $base);
  $result = ceil($result);
  $result = pow($base, $result);

  return $result;
}
//e.g. roundToBase(17); // returns 32


// supports rounding down
function roundToBase($value, $base = 2, $down = false)
{
  $result = log($value, $base);
  $result = $down ? floor($result) : ceil($result);
  $result = pow($base, $result);

  return $result;
}

//e.g. roundToBase(17, 2, true); // returns 16