Okay, this is a very random blog item with NOTHING to do with writing. Falls into the category of weird old stuff that everyone should know. A very old friend gave me this question and was killing himself laughing at the Wikipedia entry.
See the Wikipedia page. They have no clue. https://en.wikipedia.org/wiki/Roman_dodecahedron
See the person using it to crochet. Kudos for inventing a new use for it! But sorry, doesn’t explain the variation in hole sizes. https://www.youtube.com/watch?v=poGapxsanaI
This, people, is a coin sorter. You put the mixed coins in through the largest hole, hold it over a series of containers and shake it (thus the knobs in every corner, so you can hold it in any position). Over the first container you shake it with the smallest hole at the lowest point. Over the second container you shake it with the second smallest hole at the lowest point. Etc etc. This explains the various hole sizes, the knobs on every corner, and the fact that it’s made of metal. Also that examples have been ‘found with coin hoards.’
The reason they were common in Roman areas, even in the provinces, was that the Romans had a habit of collecting taxes from people who brought in large bags of money, mixed up in all sized coinages. It was used for sorting that coinage quickly so it could be counted easily.