Default Currency Change As Set At Frontend

How do I apply all amount calculations and round-ups to be in currency of customer selection?
has two currency. YUAN , US$
IF i choice 5 YUAN product
then choice 20 products so it comes out......... 5 YUAN X 20 ----> 100 YUAN RIGHT?
but it isn;t. because it calculate by us$ .
so customer will think ...this is like ""CHEAT""
so i want set 5 YUAN x 20 product ==> 100 yuan..
means IF costumer set currency becomes default value currency.. so 5 YUAN X 20 ===> 100 YUAN..(not calculate with us$)
calculate with YUAN.
PS ---DEFAULT SETTING IS NO MEANS.. because it;s global site. US$ also becomes default currency for American. EURO also become default for European.

All calculations are made in the base currency. If you want to change this behavior, significant changes in the core of cs-cart will be required and this task will cost quite high

Please see this addon:

It can set the price in Yuan, but show in US$

If your currency exchange settings are correct then it will multiply properly.

thanks so much guys. your;s opinion and answer.

i really use .......and manage shoppping mall now.

so many people customer said "" LOOKS CHEAT""

currency i show to them YUAN ...but it does not looks right calculate for customer.

this is problem. i can not force to customer that understand... ""program default blabla"""

But you can either change the default currency to yuan or fix the exchange rate setting.