<div class="form-group">

                            <div class="col-sm-12 text-center">

                                <label for="inputName" class="col-sm-5 control-label"><abbr title="Please select how you are paying today">How Are You Paying Today? (Optional)</abbr></label>


                                    <div class="btn-group" role="group" aria-label="...">
                                      <button type="button" class="btn btn-default" data-toggle="button" name="cash" id="cash" checked><span class="glyphicon glyphicon-usd"></span> Cash</button>
                                      <button type="button" class="btn btn-default" data-toggle="button" name="card" id="card" checked><span class="glyphicon glyphicon-credit-card"></span> Card Of Some Sort</button>
                                      <button type="button" class="btn btn-default" data-toggle="button" name="IOU" id="IOU" checked><span class="glyphicon glyphicon-info-sign"></span> IOU (Favor)</button>
                                      <button type="button" class="btn btn-default" data-toggle="button" name="Other" id="Other" checked><span class="glyphicon glyphicon-question-sign"></span> Other</button>
                                    </div>

                            </div>

                        </div>
...

<?php

                            if(isset($_POST['cash']))
                            {


                                echo "cash selected";

                            }

                        ?>