The answer depends on the units used for the given quantity. It should be plainly obvious to anybody that the answer for 6.75 miles will be very different from that for 6.75 furlongs. So, without any information about the units for the given quantity, it is not possible to give a sensible answer.
6.8
675
It is: 700
674.75 rounded to the nearest whole number = 675
700
468,675 rounded to the nearest hundreds is 468,700
675
It is: 700
674 rounded to the nearest ten is 670.
674.75 rounded to the nearest whole number = 675
700
468,675 rounded to the nearest hundreds is 468,700
680
490
It is 900 when rounded to the nearest ten.
680
870
Nearest hundred? 700