How do I uncheck a checkbox that is bound by a datasource when another checkbox is selected

I have a checkboxlist that populates from a sql datasource.  By default "None" is checked,  However, if the user checks one or more other checkboxes in that checkboxlist, I need to un-select "None".  I've always dealt with radio buttons before, but can't in this situation, as the user can select more than one item.   Is it possible to uncheck "None" when a user select any other checkbox in this list? 
<asp:CheckBoxList ID="cbTR" runat="server" DataSourceID="dsgetcbTR" DataTextField="Item" DataValueField="ItemID" AppendDataBoundItems="True"><asp:ListItem Selected="True" Text="None" Value=""></asp:ListItem> </asp:CheckBoxList>