300 year old Chinese Qing Dynasty Coin & early 1900s Republic of China coins

I was rummaging around my grandpa's stash of old stuff a few months ago and brought home a bunch of old "historical artifacts."

I only got around to cataloging them today, and one of them appears to be an old Chinese coin from the Qing Dynasty. It's marked with "Kang-xi Tong-Bao" (in Chinese) on one side, who was an was emperor from 1661-1722; I have reason to believe that this coin might be from that era. The other side is marked with Chinese letters that I do not recognize, and do not resemble modern Chinese. How much do you guys think this is worth?




There were also 2 more coins, from the early 20th century when the Nationalists overthrew the Qing Dynasty, and China became the Republic of China (who's government is now in Taiwan). One is a 10 cent piece, the other is a 20 cent piece. The side with Chinese is marked with something along the lines of, "celebrating a new nation." Again, how much do you guys figure these to be worth?

10 cent piece:



20 cent piece: