Whether the sale of goods or services 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. On the one hand, sales made to the casual cash-and-carry customer (such as at a gasoline station owned or operated by the enterprise), 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 enterprise is located, if delivery of the goods is made outside that State, or if the relationship with the customer is such as to indicate his out-of-State character. Such a relationship would exist, for example, where an out-of-State company in the regular course of dealing picks up the petroleum products at the bulk storage station of the enterprise and transports them out of the State in its own trucks.