YOU SAID:
I work hard at the dollar shop
INTO JAPANESE
私はドル屋で一生懸命働いています
BACK INTO ENGLISH
I am working hard at the dollar store
INTO JAPANESE
私はドルの店で一生懸命働いています
BACK INTO ENGLISH
I am working hard in a dollar store
INTO JAPANESE
私はドルの店で一生懸命働いています
BACK INTO ENGLISH
I am working hard in a dollar store
That didn't even make that much sense in English.