Words that end in -x (fox), -ch (church), -sh (wash), -ss (toss), -zz (jazz), -ce (piece), -se (purse), -ge (page) have the audible -es plural.
Most everything else is just /s/.
This is an 'off the top of my head' list. If I've left anything out, I'm sure another teacher will jump in to complete/correct my response.
- For Teachers