How to provide the Discounted price for 2nd & 3rd Product ?

Hi Experts..

Can some one suggest the pricing logic to achieve the below requirement

Basically requirement is first product should have Full price and 2nd / 3rd Product should have discounted price.

List Price of PRODUCT A : 10

Line Item 1: PRODUCT A    Quantity = 1

Line Item 2: PRODUCT A    Quantity = 1

Line Item 3: PRODUCT A    Quantity = 1

Requirement :

1) If I order the PRODUCT A  One time its price  = 10

Line Item 1: PRODUCT A    Quantity = 1  Price = 10

2) If I order the PRODUCT A  two times then

Line Item 1: PRODUCT A    Quantity = 1  Price = 10

Line Item 2: PRODUCT A    Quantity = 1  Price = 8

3) If I order the PRODUCT A  trhee times then

Line Item 1: PRODUCT A    Quantity = 1  Price = 10