What is the ruling on dealing with stores by displaying pictures of their goods online, with a request for a 10% commission from the customer as a brokerage fee, or displaying them at the same price while I receive a 10% discount from the store?

The first scenario: There is no harm in agreeing with a customer on a known commission for mediating between him and the owner of the merchandise or for endeavoring to purchase it for him.

The second scenario: If an agreement is made with the owner of the merchandise to market it, such as him saying: "Sell it for such and such, and you get ten from it," or "Whatever exceeds such and such is yours," and you sell it, then there is no harm, and you would be an agent for the seller.