If you respond N to use Standard Cost and N to "Is this the final quantity for this WO?" then the program uses a prorated calculation to calculate the cost.  For BOM Components and Routing sequences that have had some time or material reported to them, the program projects the % complete to 100% and then divides that cost by the WO Quantity to get a unit cost contribution for the specific component or labor sequence.  For any sequence or component that has had nothing reported against it, the program uses the estimated cost for that item to get its contribution.
 
If you have accurate standard costs, it may be better to use standard cost for partial receipts and then resolve the variance with the final receipt by responding Y to "Is this the final receipt?" or else use Standard Cost for all WO receipts and then when the WO is closed, any variance between the standard and actual costs will post to WIP Variance.

You can't get costs into parts that have already shipped.  That is why the WIP Variance logic exists for closing WO that get costs posted after the Finished Production is complete and parts have shipped.
 
Today's IS Tech Support (7/4/03) update introduces logic in WO-J Close Work Order that will post WIP Variance costs to the items in stock but only for the number of items that are still in on-hand stock. If the stock has shipped, the costs will still go to WIP Variance.

We have a situation with the actual cost when closing a particular w/o. If we say yes to this is the last production entry the actual cost goes to $2K plus, if we say no, then the cost is $233. The original qty was for 300 pcs we have enter production 32 time, there's only 1 pc left to complete the w/o. All the other times when we had enter production the cost had stay around $233
Can you tell me what's going on?
Thx
JI