In our school, we started a savings association for the employees. The rules are as follows:

1. The savings association is open to all [OUR SCHOOL NAME HERE] employees.
2. A member can deposit any amount in increments of 100 pesos. Cash deposited before the 10th of the month is credited to the current month; after that, it is credited to the next month.
3. The computation for the dividend is as follows. Each “share” of 100 pesos is given the following weight, based on the month it was deposited in: January – 11; February – 10; March – 9; and so on. On or before December 15, 2009, all shares are counted, and the total dividend is divided by the total number of shares. A member will receive his original deposit plus his dividend.
4. A member may stop contributing to the fund any time he wishes, however, his contribution will not be refunded until at the end of the year. This is also true for any member who may leave the school any time within the year.
5. A member may borrow from the fund, subject to 5% interest. For those who had deposited 800 pesos or less, the maximum loanable amount is twice that of the deposited amount; for those who deposited more than 800 pesos, the maximum loanable amount is 2.5 x that of the deposited amount, provided that no loan shall be more than 5,000 pesos. The loan must be paid within two months. A member may not loan any amount while he has still a pending loan. The maximum loanable amount is 5,000 pesos. If after two months the member fail to pay his loan, he shall receive a penalty of 2% on the remaining amount to be paid, for every month or a fraction thereof that he fails to pay.
6. If, in the case that a member leaves the school without paying a loaned amount, his contribution to the fund shall be deemed as payment to the association. If after deducting his contribution to the fund the member still has something to pay, the association will try to get the payment by any legal means. If the association fails to get the payment, the remaining amount shall be deducted from the total dividend. If after deducting from the total dividend of the assocation there is still a remaining amount to be paid, it is understood that this shall be borne equally by all members, according to the number of shares each one holds.
   

An attached file shows how the point system works. (I had to use PDF since the tables could not be properly represented here.)