what is the correct syntax to loop through the records for a grouping Store?

[webarnie]

I have a grouping store that I am using to get totals. I also have to take the total of one of the columns and populate another field on the screen. I do not see any way of obtaining that value directly, therefore I was going to iterate over the collection of records and calculate it. Is this the best approach? Can you obtain the total directly or does it need to be re-calculated?
Looking at the documentation for a store, there is an each function. I am trying to use this but do not understand the documentation. Here is what I have coded but the syntax is wrong.

var quickPayStore = Ext.getCmp("quickPayGrid").store;
    	quickPayStore.each(sum, function(record) {
    		var total += record.get("amountDue");
    	});

What is the correct syntax?

[webarnie]

i figured it out.

var quickPayStore = Ext.getCmp("quickPayGrid").store;
    	var amount Due = Ext.util.Format.usMoney(quickPayStore.sum("amountDue"));