Calculate Gridview Row Total using jQuery in ASP.Net

I have below GridView, I want to add Tax into Total Column formula (Amount*Tax) = Total

Below html 

<script type="text/javascript">
    $(function () {
        $("[id*=txtrate]").val("0");
    });
    $("body").on("change keyup", "[id*=txtrate]", function () {
        //Check whether Quantity value is valid Float number.
        var rate = parseFloat($.trim($(this).val()));
        if (isNaN(rate)) {
            rate = 0;
        }
  
        //Update the Quantity TextBox.
        $(this).val(rate);


         //Calculate and update Row Total.
        var row = $(this).closest("tr");
        $("[id*=lbtotal]", row).html(parseFloat($("td", row).eq(7).html()) * parseFloat($(this).val()));
  
        //Calculate and update Grand Total.
        var grandTotal = 0;
        $("[id*=lbtotal]").each(function () {
            grandTotal = grandTotal + parseFloat($(this).html());
        });
        $("[id*=lblGrandTotals]").html(grandTotal.toString());



  
        //Calculate and update Row Total Last Coulmn.
        var row = $(this).closest("tr");
        $("[id*=lbtotal]", row).html(parseFloat($("td", row).eq(7).html()) * parseFloat($(this).val()));
  
        //Calculate and update Grand Total.
        var grandTotal = 0;
        $("[id*=lbtotal2]").each(function () {
            grandTotal = grandTotal + parseFloat($(this).html());
        });
        $("[id*=lblGrandTotal]").html(grandTotal.toString());

        //Calculate % 
    });
</script>

<asp:GridView ID="gvSelected" runat="server" AutoGenerateColumns="false" Font-Names="Arial"
    Font-Size="11pt" AlternatingRowStyle-BackColor="#C2D69B" HeaderStyle-BackColor="green"
    EmptyDataText="No Records Selected" OnRowDataBound="gvSelected_RowDataBound"
    ShowFooter="True" OnDataBound="gvSelected_DataBound">
    <Columns>
        <asp:BoundField ItemStyle-Width="0px" DataField="GRN_DID" HeaderText="ID" />
        <asp:BoundField ItemStyle-Width="0px" DataField="GRN_ID" HeaderText="GRN" />
        <asp:BoundField ItemStyle-Width="0px" DataField="It_ID" HeaderText="ITID" />
        <asp:BoundField ItemStyle-Width="100px" DataField="imp_ibn_no" HeaderText="IB No" />
        <asp:BoundField ItemStyle-Width="150px" DataField="imp_ibn_date" DataFormatString="{0:dd/MM/yyyy}"
            HeaderText="IB Date" />
        <asp:BoundField ItemStyle-Width="150px" DataField="It_Name" HeaderText="Name" />
        <asp:BoundField ItemStyle-Width="30px" DataField="grn_qty" HeaderText="QTY" />
        <asp:BoundField ItemStyle-Width="30px" DataField="Cont" HeaderText="Container" />
        <asp:TemplateField HeaderText="Rate">
            <ItemTemplate>
                <asp:TextBox ID="txtrate" runat="server" Width="50px" Text='<%#Eval("txtrate")%>'></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Amount">
            <ItemTemplate>
                <asp:Label ID="lbtotal" runat="server" Width="50px" Text='<%#Bind("lbtotal")%>'></asp:Label>
            </ItemTemplate>
            <FooterTemplate>
                <asp:Label ID="lblGrandTotals" runat="server"></asp:Label>
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Tax">
            <ItemTemplate>
                <asp:Label ID="Im_Tax" runat="server" Width="50px" Text='<%#Eval("Im_Tax")%>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Total">
            <ItemTemplate>
                <asp:Label ID="lbtotal2" runat="server" Width="50px" Text='<%#Bind("lbtotal2")%>'></asp:Label>
            </ItemTemplate>
            <FooterTemplate>
                <asp:Label ID="lblGrandTotal" runat="server"></asp:Label>
            </FooterTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>