What is the ruling on selling goods electronically through a website that takes 10% of the total sale price in exchange for advertising? And is it permissible to buy from this website, knowing that the seller is charged this percentage?

There is no objection to dealing with this website, and there is no objection to the website taking a known fee for advertising the commodity, provided that the fee is known. This percentage (10%) of the total price is considered known if the price is known. Even if this percentage is only from the profit, it is valid according to the Hanbali school of thought.