e.g. the calculated line item price on an order table normally is not functionally dependent on the current price in the inventory table because the inventory price will change whereas the order price usually will not.
I believe 99% of businesses would want the UnitSalePrice, SaleQty to be saved regardless if the UnitSalePrice was taken directly from another table or calculated some way.
The result of SaleQty * UnitSalePrice is arguable (my vote is do not save).
Most argument relates to large databases that take a long time to recalculate, say, Monthly Sales Statistics and by saving SaleTotal, you only need to sum the 2,000,000 invoices rather then recalculate the 20,000,000 line items.
This argument becomes speed related rather then Normalisation.
Early databases never had this issue because we assumed Statistics were run overnight and available (spread all over the floor) in the morning.
Now we want statistics at the drop of a hat.