Whether the sale or service is made to an out-of-State customer is a
question of fact. In order for a customer to be considered an out-of-
State customer, some specific relationship between him and the seller
has to exist to indicate his out-of-State character. Sales made to the
casual cash-and-carry customer of a retail or service establishment,
who, for all practical purposes, is indistinguishable from the mass of
customers who visit the establishment, are sales made within the State
even though the seller knows or has reason to believe, because of his
proximity to the State line or because he is frequented by tourists,
that some of the customers who visit his establishment reside outside
the State. If the customer is of that type, sales made to him are sales
made within the State even if the seller knows in the particular
instance that the customer resides outside the State. On the other hand,
a sale is made to an out-of-State customer and, therefore, is not a sale
made ``within the State'' in which the establishment is located, if
delivery of the goods is made outside the State. It should be noted that
sales of goods or services that are conditioned upon acceptance or
rejection by an out-of-State source are interstates sales and not sales
made within the State for purposes of section 13(a)(2). For example, a
contract entered into in the
State where the customer resides for the delivery of a magazine to the
customer's residence, is an interstate sale if the contract must be
approved by the out-of-State home office of the company publishing the
magazine before it becomes effective.