What are the rules for rounding in math?

As a general rule of thumb, numbers should be rounded down if the final digit in a number is from 0 to 4, and rounded up if it's 5 to 9. Rounding sometimes involves more than one digit; some situations may call for rounding to the nearest hundred or thousand.

Rounding is useful in academic mathematics courses as well as in practical situations in real life. For example if an item costs $1.99 and another item costs $2.49, it is beneficial to estimate their respective costs as $2.00 and $2.50, especially when keeping track of a fixed amount of money available to make purchases.