Euro can be pluralized in either way, but it's colloquial (word of the day :)). I'm English and I would say five euros, but I have Irish friends who say five euro. I don't think it matters. It doesn't get capitalized outside normal convention - at the start of a sentence, for example. It's five million dollars, not five millions of dollars. "He has five million dollars". You would use millions more generally: there are millions of people living in London.

Hello! We talk about dollars and euros when there is more than one - so yes they get an -s on the end. Not all currency's are like that, though. My own currency doesn't have an -s on the end when we talk about more than one. If you speak about more than one million dollars then there will be an -s at the end - millions of dollars. But if there is an amount specified before the word million then it doesn't have an -s at the end - 5 million dollars. And I would say that when you speak of "five million dollars" - "five million" is the adjective and "dollars" is the noun so you wouldn't need to use the determiner "of" in-between as a determiner would only be needed if you were indicating the relationship between the two. But if you say are speaking about more than one million dollars without knowing the exact amount then you would say"millions of dollars" - there is not an exact amount so we have to use the preposition "of" to show the connection between an almost random amount and "dollars". I hope that helps!

Thank you Rahim!

Euros and dollars. They get pluralized. We dont capitalize dollars 5 million dollars. Hope this helped!