regarding sales taxes, I am assuming Apple gives back the sales taxes it collects to the appropriate gov.
Regarding corporate income tax:
For hardware, the way I understand it Apple pays its income tax in every EU countries then send the money into Ireland. So its a cash placeholder and it affects US Tax not EU tax. Ireland is a good place to hold cash because Apple can invest its cash and only pay 2% in tax to Ireland on the interest it makes.
For software and...