The answer is contained in the following quote:
Each blue ticket was pay for two verses of the recitation. Ten blue tickets equaled a red one, and could be exchanged for it; ten red tickets equaled a yellow one; for ten yellow tickets the superintendent gave a very plainly bound Bible (worthy forty cents in those easy times) to the pupil.
So, the reward for ten yellow tickets is a Bible.
The problem with this is the math involved; if one blue ticket is worth 2 verses, a red ticket worth 20, and a yellow ticket worth 200, then earning the Bible requires reciting 2000 passages. Neither Tom nor the other boys really have any interest in so daunting a task, but Tom wants the Bible anyway, although more for the sake of prestige than out of any real religious devotion. Tom trades a variety of things, such as marbles, for the other boy's tickets. Tom does end up getting the Bible, but his lack of real knowledge about its contents becomes apparent the moment that he is tested.