Traditionally (in the UK), it was reserved for large, varied shops like department stores. However, the American usage to mean any shop has certainly been spreading in business-speak for a fair while.
From the OED (the entry has not been updated recently):
> Chiefly N. Amer. and elsewhere outside the U.K. In early use, a shop on a large scale, and dealing in a great variety of articles (see quot. 18082). Now, equivalent to the British use of shop n. 3.
> The use of the word in this sense has not become common in the U.K. except in Comb., as chain store n. at chain n. Compounds 3, department store n. at department n. 5 (see under the first elements), store detective n. at Compounds 1d(a), in which it still refers to a large shop.
From the OED (the entry has not been updated recently):
> Chiefly N. Amer. and elsewhere outside the U.K. In early use, a shop on a large scale, and dealing in a great variety of articles (see quot. 18082). Now, equivalent to the British use of shop n. 3.
> The use of the word in this sense has not become common in the U.K. except in Comb., as chain store n. at chain n. Compounds 3, department store n. at department n. 5 (see under the first elements), store detective n. at Compounds 1d(a), in which it still refers to a large shop.