The advice you read is actually incorrect. The choice between "is" and "are" is not based on the type of thing you are counting, but whether you think of it as a single thing or a collection of several things. If there is a singular noun AFTER "be", use "is". If there is plural noun or no noun, use "are".
followed by a singular noun
3 million dollars IS the minimum price.
5 million dogs IS a disturbingly large population-we might need to kill some of them.
Followed by a plural noun
When I look at your collection of dollar bills, I can see that two dollars ARE American banknotes, and three dollars ARE Canadian banknotes
I have 5 dogs. 3 dogs ARE collies, and 2 dogs ARE Great Danes.
Followed by something else
5 million dollars ARE in my bank account.
In this pile, 5 million dollars ARE damaged, and 2 million aren't.
5 dogs ARE happy, and two dogs ARE angry.
500 dogs ARE in the pound.
So, your example (2) is correct, but for example (1), you should say "There ARE 2 million dollars in the case." However, this is a relatively advanced point, and even natives might say "there is" instead of "there are".