The coinback ratio is fixed based on the previous day’s price of the cryptocurrency at 11 pm (KST). If the previous day's 11 pm price of Xank was 1,000 won, then the coinback you receive today will be based on that value. Let’s say you shop at Xank Market and receive 10% coinback for a 100,000 won purchase. You will get 2,000 won in bitcoin and 8,000 won in Xank, and since yesterday's 11 pm price of Xank was 1,000 won, then you will get 8 Xank for a total of 8,000 won in Xank. You will also receive 2,000 won in bitcoin-based on the previous day’s 11 pm price of bitcoin.