Letters after dates in coin lists

I have a Deutsches Reich 5 pfennig coin.  When I looked it up all the coins from that date had a letter after the date, what does the letter mean?  Thanks!

That would be the mint mark.  Tells what city the coin was made in.

Thanks, I don't see a letter on this one; where would it be?

Which coin is it specifically?

It should be somewhere on the coin.

this one is on the obverse at the top of the coin
https://en.numista.com/catalogue/pieces851.html
this one is on the reverse below the 5
https://en.numista.com/catalogue/pieces1911.html
this one is the same as above
https://en.numista.com/catalogue/pieces1917.html
and also this one is the same
https://en.numista.com/catalogue/pieces15746.html
this last one is to the left of the date
https://en.numista.com/catalogue/pieces6312.html

It's a 1910, it almost looks like the letter A at the bottom on both sides of the tail.

 I would agree.  

https://en.numista.com/catalogue/pieces1916.html



  I also have an A and an F as well; but the letters do tend to get worn easily; the F on the right of the tail is hardly visible on mine. Welcome to the site.  

Thanks!  Is there a way to find out a value?  I have coin dealer here but every time I take something in to find out what it might be worth I just get a note with what he'll buy them for.  Really frustrating. I have a number of error bills from the US mint.

http://www.ngccoin.com/poplookup/World-Coin-Price-Guide.aspx