Rounding numbers to 2 digits after comma

Question

I have no idea how to do this? I\'m adding comma numbers, result is of course always a number with way too many digits after the comma. anyone?

Answer 1

I use this:

function round(value, precision) {

	if(precision == 0)
		return Math.round(value);  	

	exp = 1;
	for(i=0;i<precision;i++)
		exp *= 10;

	return Math.round(value*exp)/exp;
}

Answer 2

Though we have many answers here with plenty of useful suggestions, each of them still misses some steps.
So here is a complete solution wrapped into small function:

function roundToTwoDigitsAfterComma(floatNumber) {
    return parseFloat((Math.round(floatNumber * 100) / 100).toFixed(2));
}

Just in case you are interested how this works:

1. Multiple with 100 and then do round to keep precision of 2 digits after comma
2. Divide back into 100 and use toFixed(2) to keep 2 digits after comma and throw other unuseful part
3. Convert it back to float by using parseFloat() function as toFixed(2) returns string instead

Note: If you keep last 2 digits after comma because of working with monetary values, and doing financial calculations keep in mind that it's not a good idea and you'd better use integer values instead.