When teaching rounding from the ones place, we use a system known as "punching it up or putting your hands down." Children use their hands to count to the number in the ones place. If the number would require you to put up five or more fingers to count to it then you would be able to make a fist (as a fist takes five fingers) so you can punch it up, meaning you can round it up. If you can't make a fist you put your hands down, and you round down. The kids really remember this way to round and you see their little hands punching during the test.