Since you are executing the RMToggle function whenever a checkbox is selected, extend it a little by passing in the IDs too. (I've changed the IDs as well):

<div class="someRow" style="width: 100%">
    <asp:CheckBox ID="Open" runat="server" ClientIDMode="Static" Checked="true" onclick="RMToggle(this)" />
    <asp:CheckBox ID="New" runat="server" ClientIDMode="Static" onclick="RMToggle(this)" />
    <asp:CheckBox ID="Closed" runat="server" ClientIDMode="Static" onclick="RMToggle(this)" />
    <asp:CheckBox ID="Rejected" runat="server" ClientIDMode="Static" onclick="RMToggle(this)" />
</div>

Now, moving to the toggle function:

function RMToggle( elm ) { // elm = element
    var ischecked = elm.checked,
        $target = $('#table1 tr[data-id="' + elm.id + '"]');
    if( ischecked ) {
        $target.show();
    }
    else {
        $target.hide();
    }
}

Since you are executing the RMToggle function whenever a checkbox is selected, extend it a little by passing in the IDs too. (I've changed the IDs as well):

<div class="someRow" style="width: 100%">
    <asp:CheckBox ID="Open" runat="server" ClientIDMode="Static" Checked="true" onclick="RMToggle(this)" />
    <asp:CheckBox ID="New" runat="server" ClientIDMode="Static" onclick="RMToggle(this)" />
    <asp:CheckBox ID="Closed" runat="server" ClientIDMode="Static" onclick="RMToggle(this)" />
    <asp:CheckBox ID="Rejected" runat="server" ClientIDMode="Static" onclick="RMToggle(this)" />
</div>

Now, moving to the toggle function:

function RMToggle( elm ) { // elm = element
    var ischecked = elm.checked,
        $target = $('#table1 tr[data-id="' + elm.id + '"]');
    $target.toggle( ischecked );
}