So if the cost is fixed and you won’t purchase why you track inventory? You may not need inventory at all.
For example:
Create a Cost Tag for your products and Enter Fixed Costs there.
… and create a report like that.
[REPORT:2,1, 1, 1, 1]
>Name|Quantity|Sold|Cost|Rate
{REPORT ORDER DETAILS:O.MenuItemName,
O.Quantity.sum,
O.ExactTotal.sum,
([MT.Cost]*[O.Quantity]).sum,
[($3-$4)/$3];%##.00;-%##.00}
>>{REPORT ORDER DETAILS:='Total',O.Quantity.sum,O.ExactTotal.sum,([MT.Cost]*[O.Quantity]).sum,[($3-$4)/$3];%##.00;-%##.00}
MT.Cost
is the fixed cost amount you’ve configured as Product Tag.