Magnetiq

A function for rounding a decimal number to a given number of significant figures (or digits):

function sigFigs(n, sig) {
    var mult = Math.pow(10,
        sig - Math.floor(Math.log(n) / Math.LN10) - 1);
    return Math.round(n * mult) / mult;
}

alert(sigFigs(1234567, 3)); // Gives 1230000
alert(sigFigs(0.06805, 3)); // Gives 0.0681
alert(sigFigs(5, 3)); // Gives 5