Is it permissible to take a commission that includes a percentage for the bank in exchange for financing the purchase of goods?

If the bank's role is financing (paying the price then taking it back with an increase), then it is an interest-based, forbidden loan. However, if the purchase is made with the questioner's money and the bank receives a commission for transferring the money to the seller, or if the bank buys the goods for itself and takes possession of them, then sells them to the questioner, there is no harm in that. Lending with interest includes directly taking money with the condition of returning it with an increase, or the bank paying money on behalf of the client and reclaiming it from them with an increase; all of this is forbidden usury. Muslims have unanimously agreed that stipulating an increase in a loan is usury, and every loan that stipulates an increase is forbidden.