Apply tax to exiting order?

[AnnConway]

I have an order that was plced this morning where the client didn't input his postal code correctly so magento didn't apply the tax rule to his order.  Right no his order doesn't have any tax on it, but there should be a $8 fee included.  How do I go about adding that, or do I have to cancel the order and have in do it again properly?

[Brent W Peterson]

If you have already invoiced the order then you will have to cancel and redo it.