Like underquark, I was surprised by the teeny/tiny pronunciation, given that the last letter was a nun
نون
So I checked with some Arab-speaking colleagues. They unanimously go for the 'teen'.
Formal written arabic has a number of vowel symbols above and below the line which are usually omitted in day-to-day writing so perhaps these might have helped. Alternatively, I know that my compatriots in the north and west of England have wildly different vowel pronounciations from what I am used to in the south so perhaps this is a regional thing.