Keep the Change

I go to work by taxi every day. Usually the fare would either be HKD38.8 or HKD40.2. And if it is HKD40.2, normally the drivers would give me HKD60 back if I give them HKD100. I guess this is understood, because to round up to HKD41 would mean the customer would get back HKD59, which means a lot of coins and round up from HKD0.2 to HKD1.0 is quite a lot! Yesterday, this "abnormal" taxi driver did exactly that and gave me back HKD59. I did not like that and would probably avoid him next time round (if I ever meet him again).