How use jquery to add totals in gridview

I have a customized grid control that puts the Usage field in edit mode, and it allows me to just go down each row through the usage column as select the appropriate number from dropdownlist, based on quantity usage.  I got the grid to post back when the textchanged, however I don't know what row I am in, I really on get the value of the dropdownlist item.  What I need to do is take that amount and get do a calculation it and it fill the price label for that row with the calculated formula.   The formula really consists of looking up the usage in this table and taking the price from that.  Is there a better way to do this in JavaScript on the web page, or how can I get the datarow back to the code behind if that's the best way to do it.

<%@ Page Title="" Language="VB" MasterPageFile="~/ResidentConsole/Console_Master_Page1.master" AutoEventWireup="false" CodeFile="WaterSewer.aspx.vb" Inherits="ResidentConsole_WaterSewer" %>

<%@ Register Assembly="CustomGrid" Namespace="CustomGrid" TagPrefix="cc1" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">


	<%--<script type="text/javascript">
       
	</script>
--%>

<div >
	
	
</div>

	<div style="text-align: center;">
	<cc1:BulkEditGridView runat="server" ID="myGrid"  AutoGenerateColumns="False" BackColor="LightGoldenrodYellow" BorderColor="Tan" BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None" Width="616px">
		<Columns>
			<asp:TemplateField HeaderText="Unit ID">
				<ItemTemplate>
					<asp:Label ID="lblID" runat="server" Text='<%# Container.DataItemIndex %>' ></asp:Label>
				</ItemTemplate>
			</asp:TemplateField>
			<asp:TemplateField HeaderText="BldgID">
				<%--<EditItemTemplate>
					<asp:TextBox ID="TextBox3" runat="server" Text='<%# Bind("code") %>' Enabled="false"></asp:TextBox>
				</EditItemTemplate>--%>
				<ItemTemplate>
					<asp:Label ID="lblBldgID" runat="server" Text='<%# Bind("BldgID") %>'></asp:Label>
				</ItemTemplate>
			</asp:TemplateField>
			<asp:TemplateField HeaderText="Unit ID">
				<ItemTemplate>
					<asp:Label ID="lblUnitID" runat="server" Text='<%# Bind("UnitID") %>'></asp:Label>
				</ItemTemplate>
			</asp:TemplateField>
			<asp:TemplateField HeaderText="ResiID" Visible="False">
				
				<ItemTemplate>
					<asp:Label ID="lblResiID" runat="server" visible="false" Text='<%# Bind("ResiID") %>'></asp:Label>
				</ItemTemplate>
				<ItemStyle Wrap="False" />
			</asp:TemplateField>
			<asp:TemplateField HeaderText="Name">
				<ItemTemplate>
					<asp:Label ID="LblResiName" runat="server" Text='<%# Bind("ResiName") %>'></asp:Label>
				</ItemTemplate>
			</asp:TemplateField>
			<asp:TemplateField HeaderText="Usage">
				<EditItemTemplate>
					<%--<asp:TextBox ID="TextBox3" runat="server" Text='<%# Bind("Usage") %>'></asp:TextBox>--%>		<asp:DropDownList ID="ddUsage" runat="server" DataTextField='<%# Eval("Usage") %>' DataValueField='<%# Container.DataItemIndex %>' OnTextChanged="MyTestChanged" AutoPostBack="true">
						<asp:listitem Selected="True" Value="0"></asp:listitem>
						<asp:ListItem Selected="False" Value="1"></asp:ListItem>
						<asp:ListItem Selected="False" Value="2"></asp:ListItem>
						<asp:ListItem Selected="False" Value="3"></asp:ListItem>
						<asp:ListItem Selected="False" Value="4"></asp:ListItem>
					</asp:DropDownList>
				</EditItemTemplate>
				
			</asp:TemplateField>
			<asp:TemplateField HeaderText="Ext. Price">
				<%--<EditItemTemplate>
					<asp:TextBox ID="TextBox2" runat="server" Text='<%# Bind("Price") %>'></asp:TextBox>
				</EditItemTemplate>--%>
				<ItemTemplate>
					<asp:Label ID="lblPrice" runat="server" Text='<%# Bind("Price") %>'></asp:Label>
				</ItemTemplate>
			</asp:TemplateField>
		</Columns>
		<FooterStyle BackColor="Tan" />
		<PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" />
		<SelectedRowStyle BackColor="Red" ForeColor="GhostWhite" />
		<HeaderStyle BackColor="Tan" Font-Bold="True" />
		<EditRowStyle Wrap="False" />
		<AlternatingRowStyle BackColor="PaleGoldenrod" />
	
	
	</cc1:Bulkeditgridview>
</div>

</asp:Content>

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