>Like a dollar general store in USA?
Judging from your explanation, completely unlike it.
Both interior and exterior of the 100 yen stores are well established. Just a click away: http://www.daiso-sangyo.co.jp/
(the website uses the Japanese language, but I think you can enjoy the images in it)
I heard that they can sell their merchandise at reasonable price because they buy tons of goods at a time from wholesalers.