There are three general rules for rounding:
Rule 1- if the remainder beyond the last digit to be reported is less than 5, drop the last digit. Rounding to one decimal place, the number 5.3467 becomes 5.3.
Rule 2-if the remainder is greater than 5, increase the final digit by 1. The number 5.798 becomes 5.8 if rounding to 1 digit.
Rule 3- To prevent rounding bias, if the remainder is exactly 5, then round the last digit to the closest even number.Thus the number 3.55 (rounded to 1 digit) would be 3.6 (rounding up) and the number 6.450 would round to 6.4 (rounding down)if rounding to 1 decimal.
See page 12 in Hurlburt, R. (1994) Comprehending Behavioral Statistics, Brooks/Cole, Pacific Grove, CA.