I have the following formula that works in Excel, that I am trying to move to a PowerPivot calculated column.  I am getting #ERROR now.

Here is the Excel formula:

=IF([@Type]="SS",IF([@[Avail + On PO]]>0,0,ROUNDUP(([@[Avail + On PO]]*-1)/[@[MOQ ]],0)*[@[MOQ ]]),0)

My first attempt was to re-write the formula in powerpivot using the correct column references as follows:

=If([Type]="SS",IF([Avail Plus On PO]>0,0,ROUNDUP(([Avail Plus On PO]*-1)/[MOQ],0)*[MOQ]),0)

Type is text, all others are set as whole number

Does this behave as expected?

=
IF
(
  [Type]="SS",
  IF(
    [Avail Plus On PO] > 0, 
    0,
    ROUNDUP(DIVIDE([Avail Plus On PO] * -1, [MOQ]), 0) * [MOQ]
  ),
  0
)

Thank you, that did the trick.

Any recommendations on sites, books, resources where I can learn more about DAX? 

A good book is Microsoft Excel 2013: Building Data Models with PowerPivot by Marco Russo and Alberto Ferrari. There are also some good online resources such as QuickStart: Learn DAX Basics in 30 Minutes and Microsoft Virtual Academy e.g. Data Visualizations with Power BI in Excel 2013.