Form calcolo: gestione numeri decimali

[atigra]

var totale = 1.399999
totale.toFixed(2) = 1.40

Perdona la mia ignoranza, ma dove devo mettere quella cosa che mi hai indicato?
Questo è il mio codice:

<script type="text/javascript">
<!-- Begin
function startCalc(){
interval = setInterval("calc()",1);
}
function calc(){
art001 = document.autoSumForm.art001.value;
document.autoSumForm.tot_art001.value = (art001 * 1) * (1.20 * 1);

art002 = document.autoSumForm.art002.value;
document.autoSumForm.tot_art002.value = (art002 * 1) * (1.20 * 1);

art003 = document.autoSumForm.art003.value;
document.autoSumForm.tot_art003.value = (art003 * 1) * (1.20 * 1);

art004 = document.autoSumForm.art004.value;
document.autoSumForm.tot_art004.value = (art004 * 1) * (1.20 * 1);

art005 = document.autoSumForm.art005.value;
document.autoSumForm.tot_art005.value = (art005 * 1) * (1.20 * 1);

art006 = document.autoSumForm.art006.value;
document.autoSumForm.tot_art006.value = (art006 * 1) * (1.00 * 1);

art007 = document.autoSumForm.art007.value;
document.autoSumForm.tot_art007.value = (art007 * 1) * (1.00 * 1);

art008 = document.autoSumForm.art008.value;
document.autoSumForm.tot_art008.value = (art008 * 1) * (1.00 * 1);

art009 = document.autoSumForm.art009.value;
document.autoSumForm.tot_art009.value = (art009 * 1) * (0.75 * 1);

art010 = document.autoSumForm.art010.value;
document.autoSumForm.tot_art010.value = (art010 * 1) * (1.00 * 1);

document.autoSumForm.totale_generale.value = 
(document.autoSumForm.tot_art001.value * 1) + 
(document.autoSumForm.tot_art002.value * 1) +
(document.autoSumForm.tot_art003.value * 1) +
(document.autoSumForm.tot_art004.value * 1) +
(document.autoSumForm.tot_art005.value * 1) +
(document.autoSumForm.tot_art006.value * 1) +
(document.autoSumForm.tot_art007.value * 1) +
(document.autoSumForm.tot_art008.value * 1) +
(document.autoSumForm.tot_art009.value * 1) +
(document.autoSumForm.tot_art010.value * 1)
;

}
function stopCalc(){
clearInterval(interval);
}
// End -->
</script>