At a particular car park the price for parking is based on the amount of time that the car will be parked for. The charge is 1¢ for every 2 minutes for stays of 3 hours or less. The charge is then 1¢ for every 3 minutes for any amount of time after that. Customers pay money into a machine which then issues a ticket for the amount of time that has been paid for. No change is issued. Alexander is parking his car and needs to park for 2 hours 30 minutes, but only has a $1 coin. How many additional minutes will Alexander pay for?