So I've got this nifty little jquery calculator thing and I really need it to return a number so that can be passed on. Right now, it adds fine but Im not able to retrieve the info to pass to the form it belongs to.

The script...

Code:
$(document).ready(
		function (){
			// update the plug-in version
			$("#idPluginVersion").text($.Calculation.version);
			
			// bind the recalc function to the quantity fields
			$("input[name^=qty_item_]").bind("keyup", recalc);
			// run the calculation function now
			recalc();

			// automatically update the "#totalSum" field every time
			// the values are changes via the keyup event
			$("input[name^=sum]").sum("keyup", "#totalSum");
			
			// automatically update the "#totalAvg" field every time
			// the values are changes via the keyup event
			$("input[name^=avg]").avg({
				bind:"keyup"
				, selector: "#totalAvg"
				
				// if an invalid character is found, change the background color
				, onParseError: function(){
					this.css("backgroundColor", "#cc0000")
				}
				// if the error has been cleared, reset the bgcolor
				, onParseClear: function (){
					this.css("backgroundColor", "");
				}
			});
			
			// automatically update the "#minNumber" field every time
			// the values are changes via the keyup event
			$("input[name^=max]").max("keyup", {
				selector: "#numberMax"
				, oncalc: function (value, options){
					// you can use this to format the value
					$(options.selector).val(value);
				}
			});

			// this calculates the sum for some text nodes
			$("#idTotalTextSum").click(
				function (){
					// get the sum of the elements
					var sum = $(".textSum").sum();

					// update the total
					$("#totalTextSum").text(sum);
				} 
			);

		
		}
	);
	
	function recalc(){
		$("[id^=total_item]").calc(
			// the equation to use for the calculation
			"qty * price",
			// define the variables used in the equation, these can be a jQuery object
			{
				qty: $("input[name^=qty_item_]"),
				price: $("[id^=price_item_]"),
				SF_Billing_GrandTotal: $("[id^=grandTotal]").text.value
			},
			// define the formatting callback, the results of the calculation are passed to this function
			function (s){
				// return the number as a dollar amount
				return "$" + s.toFixed(2);
			},
			// define the finish callback, this runs after the calculation has been complete
			function ($this){
				// sum the total of the $("[id^=total_item]") selector
				var sum = $this.sum();
				
				$("#grandTotal").text(
					// round the results to 2 digits
					"$" + sum.toFixed(2)
					
				); 
				SF_Billing_GrandTotal = eval(grandTotal.value);
			}
		);
	}
The table...

HTML Code:
<table width="500">
				<col style="width: 50px;" />
				<col />
				<col style="width: 60px;" />
				<col style="width: 110px;" />
				<tr>
					<th>
						Qty
					</th>
					<th align="left">
						Product
					</th>
					<th>
						Price
					</th>
					<th>
						Total
					</th>
				</tr>
				<tr>
					<td align="center">
						<input type="text" name="qty_item_1" id="qty_item_1" value="0" size="2" />
					</td>
					<td>
						Learning jQuery
					</td>
					<td align="center" id="price_item_1">
						$50.00
					</td>
					<td align="center" id="total_item_1">
						$0.00
					</td>
				</tr>
				<tr>
					<td align="center">
						<input type="text" name="qty_item_2" id="qty_item_2" value="0" size="2" />
					</td>
					<td>
						Framed Award
					</td>
					<td align="center" id="price_item_2">
						$250.00
					</td>
					<td align="center" id="total_item_2">
						$0.00
					</td>
				</tr>
        <tr>
          <td></td>
          <td>Total Amount :</td>
          <td></td>
    <td align="center" id="grandTotal" ><input type="hidden" id="SF_Billing_GrandTotal" value="0" /></td>
        </tr>
			</table>
The plugin can be found at http://www.pengoworks.com/workshop/j...calculation.js and http://www.pengoworks.com/workshop/j...query.field.js

essentially, I'm trying to populate the hidden input field with the grandTotal value. Any help would be awesome! thanks