First, I will answer your original question. Below the answer, you will find all of the information I have found about other usages for "hundreds" (there are probably some that I missed).
They won hundreds of dollars; five hundreds to be precise!
As the sources below state, the author—technically—should use "hundred" in this case. However, the author used "hundreds" in the previous sentence, so they had the stylistic choice of whether they wanted to add the "-s."
In this case, the author was likely showing that the money was won in discrete units of $100. On the other hand, the author could have simply been matching the "hundreds" from the clause before the semicolon; since they are in the same sentence, it would make sense to match the plurality of the same noun. It is simply a stylistic choice by the author.
I apologize for the long(ish) answer, but you have included (since your edit) many examples, so I will give you all of the information I have found.
From A Comprehensive Grammar of the English Language (p. 308):
The nouns dozen, hundred, thousand, and million have zero plurals when they are premodified by another quantitative word:
three dozen glasses
two hundred people
The plural form is normally used with all four nouns when an of- phrase follows, with or without a preceding indefinite quantitative word:
(many) dozens of glasses
(many) hundreds of people
But the zero form is common enough:
a few million of us, several hundred/thousand of them
Note such combinations as:
tens of thousands of people
hundreds of millions of stars
From A Comprehensive Grammar of the English Language (p. 396):
We always read year date as hundreds:
In 1985 'nineteen eighty-five' [or] 'nineteen hundred and eighty five' <formal>
In the 1600s 'sixteen hundreds'
From The Cambridge Grammar of the English Language (p. 351):
i a. dozens of spiders b. hundreds of voters [head noun + complement]
ii a. a dozen spiders b. three hundred voters [determiner + head noun]
From Michael Swan's Practical English Usage (p.322):
After a number, the words dozen, hundred, thousand, million, and billion have no final -s, and of is not used. This also happens after several and a few.
five hundred pounds
hundreds of pounds
several thousand times
It cost thousands.
a few million years
millions of years
From Cambridge Dictionary:
There were hundreds of people at the pool today.
There were a hundred shirts waiting to be ironed.
He expects the total amount to be in the low hundreds.
The house was built in the sixteen hundreds.
Breakfast is at seven hundred hours.