Is it obligatory for the owner of the goods to bring 0.5 dinars to the cashier, knowing that the latter did not ask for it, after he had taken 6 dinars for goods worth 6.5 dinars, and the buyer intended to bring the remaining half if change was not available?

The buyer is not required to return anything to the cashier in the market, because there was mutual agreement on the discount, and it is customary for cashiers to overlook small amounts with explicit or implicit permission from the owner of the establishment. This method is employed in stores to incentivize and encourage buyers.