Which role is more important to increase the business? Sales assistant, Cashier or Manager?

In a Business firm, Sales Assistant, Cashier and Manager are equally important as each one has individual duties and responsibilities. To increase business in a firm, according to me, Manager is more important. A Manager can give several suggestions to their Sales Assistants and Cashiers. Managers can give blanket permissions as well as confidence to their Sales assistance. This can drive their sales assistance to use various tactics to bring out more profits and sales into an organisation.