Among 'two thousands five hundreds dollars' and 'two thousand five hundred dollars.', which is the right one?
should I put 's' at the end of thousand and hundred?
You don't use plurals with specific numbers (it's redundant), so "two thousand five hundred" is correct.
On the other hand (as pointed out by stangdon), they are used with general numbers: "dozens of times", "hundreds of years", and so on.
EDIT Similarly, you do use plurals with fractions, so .02 is "two hundredths", and 3/4 is "three fourths".