Shekalim 6 - Counting pennies
If one was collecting small coins to accumulate for his half-shekel obligation - having declared "this is for my half-shekel" - but eventually he collected more then needed, what is he to do with the surplus? Even though his designation of the surplus coins was invalid, since he did not need them in the end, it still becomes consecrated, and the money should be put into the collection box in the Temple, to be used when the Altar is idle - this is the opinion of Beit Shammai. Beit Hillel disagree: Temple consecration in error is still an error, and the money remains his. However, if he declaration was, "I will bring my shekel from this money," all agree that the extra money remains his.
What if he was collecting money for his sin-offering and collected more than he needed? Here the surplus definitely goes to the Temple. Why? Because the cost of a sin-offering does not have a fixed limit, whereas the half-shekel does - so explains Rabbi Shimon. However, Rabbi Yehudah argues with his explanation and says that the half-shekel also is not a fixed amount: when the Jews just got back from Babylon, they donated the "darkon" coin, which is 4 times more valuable, then they switched to two times more, then to half-shekels, although never less than that. So it depends on the basic currency unit. Still, Rabbi Shimon answers that the half-shekel is fixed in the sense that all give the same amount. The Talmud describes other surpluses, for example, the surplus money of the Passover sacrifice must be used for another Passover sacrifice.
Art: Merchants counting money by (after) Salomon Koninck