Returns the same cache buster value for a given number of minutes. I use it by appending '&cb=' + cacheBusterMinutes(5) for example to ensure the same URL is used for 5 minutes and then changes after 5 minutes with a different &cb querystring value.

cacheBusterMinutes.js

function cacheBusterMinutes(cache_for_minutes) {
	var d = new Date;
        return d.getFullYear() + ("0" + d.getMonth()).slice(-2) + ("0" + d.getDate()).slice(-2) + ("0" + d.getHours()).slice(-2) + ("0" + parseInt(d.getMinutes() / cache_for_minutes)).slice(-2);
}