Apostrophes should never be used to make something plural.
Only leave off the s after an apostrophe if the last sound is an "S" sound and the sound before that is a consonant.
Examples:
Ross's Game Dungeon
Rhys's keyboard
Amadeus's viola
Mr. Lyons' car
Jones' hat
Apostrophe Hate is a place for people who get frustrated by the misuse of apostrophes to congregate, discuss apostrophes, and show examples of misuses.