What is the main function of the arthmetic logic unit?

Janis owns and operates a store in a country experiencing a high rate of inflation. in order to prevent the value of money in her cash register from falling too quickly, janis sends an employee to the bank four times per day to make deposits in a interest-bearing account that protects the store's revenues from the effects of inflation. this is an example of the (menu costs/ unit of account costs/ shoesleather costs) of inflation. pick one