I have some data with which I want to build a histogram. I would like to build bins that are "uneven"

A report with Bin for histogram usually has the intervals of the same size. If you want the interval to be different then you can create a calculated field and use that calculated field as a dimension to create your report. For example, you may keep 0-10 as one category, 10-15 as another category, and so on. Later, use these categories to create your report. this way you will be able to create a histogram with uneven Bin size.