I compost all mine.
I get a load of really horrid ones from the old bedridden guy I look after and I've never found any trace of them when I dig out the
humanure heap.
I suspect there *may* be a few 'ultra tough' types that use a super-fine plastic mesh so they hold together better, so I make sure I always buy the cheapest, preferably unbleached and recycled, bog-standard tissues I can find. I guess if you're not sure, try soaking them in
water till they fall apart and see if there are any threads that don't want to dissolve into mush.
I also use those moist toilet-wipes on the old man (I feel a bit guilty because it seems so wasteful, but I'm not going to accept cricisism from anyone unless they too spend far too much time handling someone else's poop) and so long as I buy 'flushable' ones they seem to disappear without trace.