Javascript intelligent rounding

<script type="text/javascript">
    function intelliRound(num) {
        var len=(num+'').length;
        var fac=Math.pow(10,len-1);
        return Math.ceil(num/fac)*fac;
    }
    alert(intelliRound(13));
    alert(intelliRound(349));
    alert(intelliRound(5645));
    // ...
</script>

See http://jsfiddle.net/fCLjp/

One way;

var a = [13, // 20
 349, // 400
 5645, // 6000
 9892, // 10000
 13988, // 20000
 93456, // 100000
 231516 // 300000
]

for (var i in a) {
    var num = a[i];
    var scale = Math.pow(10, Math.floor(Math.log(num) / Math.LN10));
    print([ num, Math.ceil(num / scale) * scale ])
}

13,20
349,400
5645,6000
9892,10000
13988,20000
93456,100000
231516,300000

The answer from @rabudde works well, but for those that need to handle negative numbers, here's an updated version:

function intelliRound(num) {
     var len = (num + '').length;
     var result = 0;
     if (num < 0) {
         var fac = Math.pow(10, len - 2); 
         result = Math.floor(num / fac) * fac;
     }
     else {
        var fac = Math.pow(10, len - 1);
        result = Math.ceil(num / fac) * fac;
     }
     return result;
}
alert(intelliRound(13));
alert(intelliRound(349));
alert(intelliRound(5645));
            
alert(intelliRound(-13));
alert(intelliRound(-349));
alert(intelliRound(-5645));