Machatzit Hashekel

Machatzit HaShekel mitzvah was practiced while Beit HaMikdash existed, and the money was donated to Beit HaMikdash treasury.
Today the donation is given as a commemoration of the Half-Shekel and it says in the Holy books that the one who gives half a shekel is assured to earn Olam Haba (afterlife)
Even if a decree is issued against him or his family, it is annulled. And the one who perseveres the mitzvah every year will live long and prosper.
This is your opportunity to observe the mitzvah of Machatzit HaShekel
• On Taanit Esther – the “fast of Esther,” before the Mincha prayer, we give the Machatzit HaShekel to charity. Zecher Le’Machatzit Hashekel is calculated by the value of the amount worth 9.6 grams of pure silver. One Gram = $0.83 USD (9 Grams = $7.96)
Machatzit Hashekel in Israel is – 28 Shekels
• It is customary to give three coins, since the word Terumah (lit. an offering) is mentioned three times in the beginning of Parshat Ki Tisa (Exodus 30:11-34:35). If one did not manage to give it before Mincha, then he can give it after Mincha, or before the Megillah reading on Purim night or before the Megillah reading on Purim morning.
• One should not use money from his/her Maaser (tithes) for Machatzit Hashekel
• The minimum age to give is 20 years old BUT the custom is to give for every person in your household (Men, women and children) If you can afford it!
• If one can not afford the price, a half a Shekel coin is enough or even a smaller coin
• If one can afford the price and wants to give more, it is permissible and recommended 
• A father who started giving on behalf of his young children, must continue giving on their behalf every year until the child becomes responsible to give on his own, unless he explicitly made a condition [the first time that he gave for his children] that he is not accepting it upon himself as a vow. A father should also give the Machatzit Hashekel on behalf of his unborn child (during the mother’s pregnancy)
• It is customary to give the donation money to Torah learning institutes