Hay buddy,
You can use AjaxToolkit to make it done. The sample code are given below:
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<div>
<asp:Panel ID="pnlMain" runat="server">
<asp:Table ID="tbMain" runat="server">
<asp:TableRow>
<asp:TableCell>1.</asp:TableCell>
<asp:TableCell>John Smith</asp:TableCell>
<asp:TableCell>USA</asp:TableCell>
</asp:TableRow>
<asp:TableRow>
<asp:TableCell>1.</asp:TableCell>
<asp:TableCell>John Smith</asp:TableCell>
<asp:TableCell>USA</asp:TableCell>
</asp:TableRow>
<asp:TableRow>
<asp:TableCell>1.</asp:TableCell>
<asp:TableCell>John Smith</asp:TableCell>
<asp:TableCell>USA</asp:TableCell>
</asp:TableRow>
</asp:Table>
</asp:Panel>
<Ajax:RoundedCornersExtender ID="Round1" runat="server"
TargetControlID="pnlMain" Radius="5" BorderColor="Black"
/>
</div>
Don't forget to add AjaxToolkit reference in your project. :)