you look at the number and if the last digit is 5 or over, then you round up to the nearest ten. if the number is 4 or under you round down to the nearest ten. 64 would round to 60 but 65 would round to 70

65.278 is approximate to 100 to the nearest hundred 70 to the nearest ten 65 to the nearest whole number/unit 65.3 to the nearest tenth 65.38 to the nearest hundredth