Re: Customer data, no problem.
Many PoS systems request email and phone # as a way to get more marketing data. You'd be surprised at how many people give it up without a fight.
I can understand this for online orders, however... at the PoS where you're buying the product in person?
In the States you can always give them <area code> 555-1212 (informtion) or any other 555 number which is never used as a real number.