Suppose that when making a histogram, one encounters a datum at a bin boundary. Is there a convention on how to round it? For example, suppose my data are integer percentages, running from 0% to 100%. I want to make a histogram with boundaries at 10%, 20%, etc. Of course I could label the histogram in a way to avoid the issue, e.g. by labeling the categories 0-9, 10-19, etc. But suppose I don't want to label them like that. I could save space on the x axis by simply labeling the bin boundaries of 10, 20, 30, etc. But then if I encounter a datum at 20, is there a convention as to whether it goes into the 10-20 bin or the 20-30 bin?