Rodents are rarely kept, considering they make up 20% of all mammals and, like amphibians, are usually small and easy keepers. Other than the binturong, there's almost no viverrids at all in north america, especially in AZA institutions.
If I had to guess why some rodents are not often kept, I would say it’s because of their lifespan. Rodents, especially small ones (rats, mice, chipmunks) usually only live for a couple years, so I don’t think a zoo would want to invest their time and resources into something that won’t last that long anyway. However, larger rodents (capybaras, porcupines, maras, squirrels) live longer so these types of rodents are very common in zoos. Overall, usually only smaller rodents are poorly represented due to their short lifespans, but are way more common compared to other groups of mammals like elephant shrews and Prosimians.