Put this code in your CBC's footer:
<style>
.cbc .numeric_input {
display: none;
}
</style>
<script>
$(document).ready(function(){
var options = [0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50];
var dropdownHtml = '<select class="cbcDropdown">';
options.forEach(function(option){
dropdownHtml += '<option value="' + option + '">' + option + '</option>';
});
dropdownHtml += '</select>';
$('.cbc .numeric_input').each(function(){
$(this).after(dropdownHtml);
$(this).siblings('.cbcDropdown').val($(this).val());
});
$('.cbcDropdown').change(function(){
$(this).siblings('.numeric_input').val($(this).val());
$(this).siblings('.numeric_input').keyup();
});
})
</script>
Line 9 should be updated with the options you want in the dropdowns.