Let me give you a little background. The Talmud says clearly that a store in a marketplace does not require a mezuzah. This is even codified by the Shulchan Aruch. However, the Acharonim point out that these “stores” were actually temporary booths set up in what we would call “flea markets.”
But our stores are different. They are permanent structures that are also used to store merchandise, and therefore they require a mezuzah.
However, since they are not actual dwellings utilized both day and night and for sleeping as well, most authorities caution against making a berachah. It should be noted that some rabbis do rely on the opinions articulated by the Kitzur and make a berachah when affixing mezuzot on stores in certain situations.
 Yad Haketanah 2:21, cited in Pitchei Teshuvah 286:10, Aruch HaShulchan Y.D. 286:26; Sha’arei HaMezuzah 6:8:13; Agur B’ohalecha 34:39:76.
 Turei Zahav Y.D. 286:10; Chayei Adam 15:11; Beit Baruch 11:13; Misgeres HaShulchan 11:11; Teshuvos V’Hanhagos 1:647; Chovas HaDar 3:8:24; Agur B’ohalecha 34:39:76 and 78.