My bad @blocktrades, I should've addressed his question more directly lol. This made me do a much deeper dive than I intended to, but here goes. I may have gone slightly overboard with this, but it started as some back of the envelope calculations and now I've come up with the following chart. It should shed light on his specific question and case study of being the 10th voter out of 20.
Please note that @beshadow did not mention the value of the votes that came in the 9 votes preceding his 10th, thus I assumed it as being $5 for this example. You can input whatever number you like and the calculations will play out accordingly - the greater the value of the votes preceding yours, the less your curation reward will be.
Another note: as I mentioned before, it doesn't matter if 100 people vote before you or if 3 people vote before you or if 1 person votes before you. The only thing that matters is the value of the vote(s) preceding yours
you may have to zoom in on your browser to see the image. Otherwise right click and copy image address and open in your browser:
To verify my the math on these charts, example #1 uses the equations of #2 and #3 and applies them to the example provided by @miniature.tiger in his post that I linked in my first comment.
As you can see, example #1 hits the exact same result as miniature.tiger's chart, so we've verified that the equations are actually correct ;)
Conclusion
It's a very steep downward curve when it comes to not being the first voter.
If you vote on a post that is already at $5 with a $0.30 vote, and the post still goes up 4x in value to $20 after your vote, you won't make much Curation Reward at all.
However, if you're the first one who votes on a post with $0.30 and then the post goes up to $2 afterwards, you'll earn a Curation Reward that is equal to 65% the value of your original vote - a 40% increase from your original 25% curation reward.