about bitcoin market price for a shopping mall
There is a simpler option than to re-tag your products every day to keep up with ever changing prices. You could denominate the products in USD/EUR/... and advertise that you are accepting Bitcoin. Then you update your point-of-sale software to be able to do the USD/EUR/... to Bitcoin conversion on the fly, with regularly updated exchange rates. This way you always keep up to date, can give information on the current price in Bitcoin and accept Bitcoin payments, all while keeping the price tags stable.