Our customer located in Gretna, NE says the sales tax rate should be 7% and our invoices show Avatax at 5.5%. The 7% rate should apply to both their physical address and their PO Box.
Given the nature of PO Boxes, they can't always be validated. When this happens the engine falls back to the zip code (5 digits) and will calculate the rate at the center of that zip code (5 digits).
If you have a specific PO box that is not calculating a city rate please feel free to make a jurisdiction override for the zip+4 of that PO Box.
The override will only ever be triggered by that PO Box since for PO Boxes the Zip+4 will be the PO box number.