FIFO COGS finding cost per sale

[AlvinM]

I am trying to figure out how to get the COGS per individual sales in Power BI. (I put the Sales table from Power BI into excel to show it easier.)
Sales Table

 Invoices Table (Has what products are bought for the store and how much each cost)

So right now the Sales table shows the total cost of COGS for the highlighted sales of ASIN "B00HSRVBAG" for a Quantity of "8" is $22.00.  It should be a total of 1@$1.00 + 1@$2.00 + 6@$3.00 for a total of $21.00.

Currently for COGS I am using this

COGS =

var CurrentDate = Sales[customer_shipment_date]

var CurrentSoldQTY = Sales[ASIN Sales QTY Running Total]

var CurrentAsin = Sales[asin]

var CurrentQTY = Sales[quantity]

var InvoicesFilteredTable = FILTER(Invoices,CurrentSoldQTY > Invoices[Total QTY Purchased]

&& Invoices[ASIN] = CurrentAsin)

var SalesFilteredTable = FILTER(Sales,Sales[customer_shipment_date] <= CurrentDate

&& Sales[asin] = CurrentAsin)

var ExtraFilteredTable = FILTER(Invoices,CurrentSoldQTY <= Invoices[Total QTY Purchased]

&& Invoices[ASIN] = CurrentAsin)

Return

IF(Sales[quantity]>1,

SELECTCOLUMNS(TOPN(1,ExtraFilteredTable),"Rate",[Rate]) *

IF(ISNUMBER(SELECTCOLUMNS(TOPN(1,InvoicesFilteredTable),"Quantity",[quantity])),

CALCULATE(SUM(Sales[quantity]),SalesFilteredTable) - SELECTCOLUMNS(TOPN(1,InvoicesFilteredTable),"Quantity",[quantity]),

BLANK()

) + IF(ISBLANK(SELECTCOLUMNS(TOPN(1,InvoicesFilteredTable),"Quantity",[quantity])),

BLANK(),

SELECTCOLUMNS(TOPN(1,InvoicesFilteredTable),"Rate",[Rate]) * SELECTCOLUMNS(TOPN(1,InvoicesFilteredTable),"Quantity",[quantity])

),

SELECTCOLUMNS(TOPN(1,ExtraFilteredTable),"Rate",[Rate]) * CurrentQTY)

Which get the right COGS if there is only 2 different purchasing cost it has to look at but once an order has to go through more than 2 different COGS price changes it stops.

Thanks for any help.

[lbendlin]

Please provide sample data that covers your issue or question completely, in a usable format (not as a screenshot).
https://community.powerbi.com/t5/Community-Blog/How-to-provide-sample-data-in-the-Power-BI-Forum/ba-...
Please show the expected outcome based on the sample data you provided.

https://community.powerbi.com/t5/Desktop/How-to-Get-Your-Question-Answered-Quickly/m-p/1447523