how do i add discount function for USPS ship method?

[gueston]

Hi
Everyone,help me please
You know,the china EMS (USPS) cost is too much,but it is great ship for small order.so we need it,and many post can give us discount,as 70% discount.So we need give 70% discount for our client.then i need a discount function for china ems .

i need the function will account ship cost,and the ems price as below:
US,CA
0.5:240,1.0:295
AU,NZ,PG,BN,NC
0.5:245,1.0:295
(i need copy the price in admin)
but if have discount funtion ,then only have 168 for 0.5kg (70%) to US.

Thanks
My MSN: [email protected]