When a number is 0, 1, 2, 3 or 4 it rounds down. When a number is 5, 6, 7, 8 or 9 it rounds up. In the case of 73375.5201 the tens digit is a 7 so you round up. The answer is 73400.
117 rounded to the nearest 100 = 100
100
100
853 rounded to the nearest 100: 900. 10853 rounded to the nearest 100: 10900.
100
Rounded to the nearest 100 it is 300
100
100
4496 rounded to the nearest 100 is 4500.
100
100
100