In one year, the mcalister family drove their car 15,680 miles. to the nearest thousand, how many miles did they drive their car that year?

The answer is 16,000

16,000 miles.
You need to round up from the hundreds.
As a rule of thumb, if the number after the number you're rounding is above 5, round up; if not, round down.
Like if I was rounding to tens:
38 rounds up to 40
34 rounds down to 30.
Anyways, in this case, then, we round 15680 up to 16000 miles.