Finding the SUM of a list of numbers inside a bullet list

Hi all,

I’ve been scratching my head on this one, my needs are quite simple, all I need to do is show a SUM of prices that are listed in a repeater bullet list, no matter what I try I just cant get it to show a SUM total. The repeat region data is taken from a db join that pulls the ‘PricingPrice’ data from an array inside a bookings table.

Heres what I have so far

<ul>
                                                <li dmx-repeat:repeat1="scServicesList.data.queryServices" dmx-show="dataBookingDetails.data.BookingServicesRequired.contains(PricingID)">
                                                    £{{PricingPrice.toNumber()}} {{PricingTitle}}
                                                </li>

                                                sum = {{PricingPrice.sum()}}


                                            </ul>

Front end is here:

Can anybody put me out of my misery…?