How to round in javascript like PHP do

You can use toPrecision Function

It will rounded by the precision provided. Here I rounded by 4 to get 6.405 and then rounded by 3 to get 6.41

parseFloat((6.404999999999999).toPrecision(4)).toPrecision(3);

console.log(parseFloat((6.404999999999999).toPrecision(4)).toPrecision(3));

I think the best answer is the next:

function roundLikePHP(num, dec){
  var num_sign = num >= 0 ? 1 : -1;
  return parseFloat((Math.round((num * Math.pow(10, dec)) + (num_sign * 0.0001)) / Math.pow(10, dec)).toFixed(dec));
}

I tried the other solutions with 1.015 and doesn't work as expected.

This solution works well, like PHP round, with all the numbers I tried.