Calculations from ticket tags

Hi Guys,

Can you point me in the right direction.

I have a ticket tag setup to record my restaurant covers.

Is there a way I can just get a total of all the orders tagged instead of a list.

So if I have two table of 3 I just want to report that I had a total of 6

Hope this makes sense.
I have this so far
{REPORT TICKET DETAILS:TT.Covers:(TY=Bistro Staff Food)}

but this just lists the total value per tag.

Please help thanks.

Try .Sum

{REPORT TICKET DETAILS:TT.Covers.Sum:(TY=Bistro Staff Food)}