I have never seen it open, ever. I click on the till but it says the store is closed. I had my sim paint something then put the painting in their inventory and take it to the store and hang it on the wall, is it supposed to sell? I don't get it. How do I open the store? lol
...and you don't want to hang your painting there. If it's working and open, then there will be someone standing behind the counter. Click on the cash register and select 'buy'. You'll get a tab in the buy window for selling objects on consignment.