The law does not say that you get overtime if you work over 8 hours in a day. It says you get overtime if you work over 40 hours in a week. So working 10 hours a day is meaningless when it comes to overtime. What matters is the total number of hours for the week.
If you are working 4 ten hour days, no overtime is due. If you are working 5 ten hour days, it is, not because of how many hours you worked in a day, but because of how many hours you worked in a week.

