FYI- the Zebra MC40 seems to have an issue with Interleaved 2 of 5  barcode format, aka, ITF, when passing barcode data to the quickbooks app.  It just won't do it.

My team has in the neighborhood of 40-50 man hours in attempting to solve this problem, before we found out from the hardware distributor that it's a known issue. Neither Zebra support nor QB Support , that we talked to, had heard of this issue.