How can I elegantize this verbose jquery?

I need to get the value of the checked checkbox (only one is allowed to be checked at a time), and I have this verbose code to do so:

if (!checkboxSelected) {
    return;
}

if($("#ckbx_produceusage").is(':checked')) {
    rptval = $('#ckbx_produceusage').val();
}
else if($("#ckbx_deliveryperformance").is(':checked')) {
    rptval = $('#ckbx_deliveryperformance').val();
}
else if($("#ckbx_fillrate").is(':checked')) {
    rptval = $('#ckbx_fillrate').val();
}
else if($("#ckbx_pricecompliance").is(':checked')) {
    rptval = $('#ckbx_pricecompliance').val();
}
setEmailAndGenerateValsForUnitReportPair(unitval, rptval);

Is there a way I can make this code less verbose without making it ungrokkable? I thought of dynamically adding a class to the checkbox that is checked, and then removing it from any that previously had that class added, and then getting the rptval based on which one is currently decorated with that class. That seems a bit smelly or Rubegoldbergesque, though, so am looking for a better solution.

UPDATE

For T.J. Crowder, here is the HTML (Razor/ASP.NET MVC style):

@foreach (var rpt in reports)
{
    @* convert id to lowercase and no spaces *@
    var morphedRptName = @rpt.report.Replace(" ", string.Empty).ToLower();
    <input class="ckbx leftmargin8" id="ckbx_@(morphedRptName)" type="checkbox" value="@rpt.report" />@rpt.report
}

$(function()
{
...
// IF (these are the only elements that id starts with ckbx_) THEN
    rptval = $('[id^=ckbx_]').filter(':checked').val();
// ELSE
    // this syntax is more maintainable than $('#ckbx_produceusage, #ckbx_fillrate, ... selectors à la queue');
    rptval = $('#ckbx_produceusage').add('#ckbx_fillrate').add('#ckbx_deliveryperformance').add('#ckbx_pricecompliance').filter(':checked').val();
// FI
...
});