What are the main duties of a cashier at Mcdonald's?

The cashier is responsible for a successful checkout - which basically includes all the things the secret shopper is asked to look for.

eye contact, smile, greet, check out in a timely manner, careful packing, safeway and airmiles card, offer carry out, thank by name, parting comment.

most of the duties take place at the till, but the cashier may be asked to perform other duties depending on need, etc.

Other duties I've performed - trainee shadow (based on experience and seniority), wash tills (in the evening, when it's slow), face shelves (at slow periods, generally in the evening), stock shelves (based on staff/need), breaks (generally assigned to ~2 people per day, relieve other cashiers for their breaks), assist at customer service (requires some training, based on experience and seniority), collect coupons/put out call sheets (coupons daily in the evening, call sheets based on availability), assist customer service clerk with their duties (ie. changing changers, closing tills, etc), bagging for other cashiers (based on need for cashiers/how busy it is), etc.

most of these other duties occur in evening shifts.