In reply to:
That should work. The microformats1 hReview property details specified "fixed decimal point (one decimal point of precision)," which should carry over for backward compatibility: https://microformats.org/wiki/hreview#Property_details
Cool, thanks for the link and explanation. I did find something in the microformats2 spec regarding h-review, but there it just says for p-rating value from 1-5 indicating a rating for the item (5 best), which is a bit thin documentation-wise. 🙂