Calculate employee wage
My first review in awhile, this is short, sorry. I'm sure others will add more. 


Please stop doing using namespace std. Read
this.
Using double for representing currency is
bad.
But since this is an assignment, it probably won't matter much.
Use constant variables to represent magic numbers like .15 and
3.0. Create a const variable named TAX_RATE for instance.
You are returning an int yet salary is of type double?
time_t curTime = time(NULL);

Use
nullptr
(C++11).