Edit in JSFiddle

<meter id="meter" value="5" min="0" max="100" low="30" high="60" optimum="90">Your browser doesn't support meters. However, we're currently at <span id="meter-backup">5</span>%</meter>
var meter = document.getElementById("meter"),
    meterbackup = document.getElementById("meter-backup"),
    interval = 5,
    updater;

updater = setInterval(function(){
    meter.value = meter.value + interval;
    meterbackup.innerHTML = meter.value;
    
    if (meter.value >= 100) {
        clearInterval(updater);
        /* Maybe make sure everything is set to 100
        if your interval is not divisible by 100 */
        meter.parentNode.insertAdjacentHTML("beforeEnd", "Done!");
    }
}, 500);