I found a bug and several problems in cart [VM2.0.16]

[superie]

My version is Joomla 2.5.8 and VirtueMart 2.0.16.
1. The virtuemart default currency is United Stated Dollar, List of accepted currencies are Euro, USD...
The currency rate was set already, the converted  unit price Euro is right, but after I times a quantity(eg. 100*0.31euro, as the following picture shows),
the total amount in cart should be 31 euro, not 30.69 euro. Attached picture FYR.

2. How can I change orders content at the VirtueMart back end? eg. Shipment Fee.
Coz we have different delivery ways with different  charge(by weight, by volume), sometimes we have to enter into shipping cost manually.
plus the amount of products , then buyers pay.

3. My suggestion:  Maybe a super administrator  should have the right to modify orders details,  other authorized administrator should also have the authority.








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[Milbo]

Please read http://forum.virtuemart.net/index.php?topic=111470.msg374867#msg374867
and
http://forum.virtuemart.net/index.php?topic=108809.msg367089#msg367089

[superie]

Thanks for your kind reply.Milbo
but still unsolved.
I don't have any tax. what I need is the total amount of the support currency (Euro)should be correct. the based default currency is USD
100*0,31euro should be 31,00euros.  seems not the matter of rounding
Any one can help with？

[Milbo]

So the rate between € and $ is an integer and need not to be rounded?

[superie]

The default currency is USD, I'd like to show either EURO or USD prices, users can choose Euro or USD by clicking  Store Currencies
If I set the euro currency rate to an integer (eg.  1.00), I choose  Store Currencies  as  Euro  ,  unit price shows correctly( 0.31 euro),
after I select a quantity  (eg .   100), click "Add to Cart",  then " Show Cart",
unit price   0.31€, quantity    100,   total    31.00€

But if I set the euro currency rate to a decimal   (eg.  0.78) ,I choose  Store Currencies  as  Euro  ,  unit price shows correctly( 0.31 euro),
after I select a quantity  (eg .   100), click "Add to Cart",  then " Show Cart",
unit price   0.31€, quantity    100,   total    30.69€

I've tried to change rounding decimals, but still wrong total in cart.
an integer  rate shows correct total , a decimal rate shows wrong total.
The post you recommended doesn't help.
Could you help with?

[Milbo]

read the post, understand rounding. You may change in the config the new option to get from your point of view more "correct" results (even they are from math point more incorrect).