Coins or potsherds were used to keep the eyes closed in death. The use of coins was picked up from the Greek occupation, but the practice of potsherds was quite well established. Skulls from a 1st Century Jewish burials in a Jerusalem Cemetery were found to have a either sherds or coins in some of the eye sockets when excavated. The majority found with one or the other had potsherds, but a fairly large percentage were found with small denomination coins in the sockets.
Joseph of Aramethia was a wealthy man supposedly, so it wouldn’t be a stretch for him to use small coins.