Rather than mess around with what you posted I wrote something that does what I think you're asking for. You can choose the amount per day and/or the start figure, and it increments in cents. And it's short (shorter than this post

).
In the code below it's 1000 (or thereabouts) and 500 for the daily increase just to see it working, because $5/6 a day increases at a boring 1 cent every ~3 minutes.
BTW the higher the daily figure the higher the start figure, because it's client side script. Everyone's computer clock is different and it needs a fixed base time to compare to, long enough ago to be in the past for the whole world, and the number will be different for everyone in the world. This isn't an issue with $5 a day, but with 500, as below, you might be wondering why it's so much over 1000.
I must have misread your post because I thought you required commas. Rather than bloat it with another function I added a couple of lines for one comma, which is all you need for any number up to 999,999. If you start at $1000 and increase at $5 a day it will take about 550 years before that becomes an issue. I'll be happy to fix it if I'm around then.
As for people asking for money for a few lines of jabbascript... are you shitting me?
Hope it helps.
Code:
<html>
<head>
<script type="text/javascript">
function saved(){
var start = 1000; // start figure (appr)
var perday = 500; // amount per day increase
var spd = 86400000/perday;
var update = spd/100;
var now = +new Date();
var basetime = 1305100000000;
var dif = now - basetime;
var money = dif/spd + start;
var save = (Math.round(money*100)/100).toFixed(2);
var len = save.length;
var save = save.substring(0, len-6) + "," + save.substring(len-6);
document.getElementById('txt').innerHTML="Our customers have saved $"+save+" with us. ";
t=setTimeout('saved()',update);
}
</script>
</head>
<body onload="saved()">
<div id="txt">If you can read this something went wrong.</div>
</body>
</html>