There's technically no such thing as "overtime", since tennis matches end based on the score rather than a time limit. Extra points played at the end of a set, when the score is too close (because a player needs to win the set by at least two games), are called a tiebreaker.
Guyana's money is callled dolor
It is called the Coccyx.
The noun overtime is an uncountable noun. Multiples are expressed in terms of 'hours of overtime', 'more overtime', 'some overtime', etc.
She has a store callled About Face!