say admin set three rates for reseller:
default     0.2        for all resellers
0086        0.25     for reseller1
00852     0.3        for all resellers

then reseller1 logged in and want to add sell rate for his callshop

1. we add rate for North Americe, which prefix is 001, it will give the buy rate for 001 after input box (we didnt set prefix 001 in rate to reseller, so it will use default rate)

2. we add rate for China, which prefix is 0086, it will give the buy rate for 0086 after input box

3. we add rate for HK, which prefix is 00852, it will give the buy rate for 00852after input box

also, when groupadmin add customer sell rate, he can also see his buy rate from reseller