If the measurement doesn't reach the 1/2 inch mark between inch markers, round down to the whole inch. If the measurement is at or above 1/2 inch, use the half inch mark in your measurment.
Locate the nearest inch or half-inch mark and use that to express your measurement.
If the measurement is exactly on the 1/4 inch mark, you round up to the nearest 1/2 inch. Likewise, if the measurement is exactly on the 3/4 inch mark, you round up to the nearest whole inch.
In this illustration, each angle bracket and arrow shows a range and the nearest half-inch to which it will be rounded. Each quarter gets rounded up to the nearest half/whole.
If the measurement is exactly on the 1/4 inch mark, you round up to the nearest 1/2 inch. Likewise, if the measurement is exactly on the 3/4 inch mark, you round up to the nearest whole inch.
In this illustration, each angle bracket and arrow shows a range and the nearest half-inch to which it will be rounded. Each quarter gets rounded up to the nearest half/whole.