A bid will only be considered by eBay if it's by the required bid increment higher than the displayed bid.
This bid is called minimum bid.
The bid increments vary and differ depending on the eBay country domains. Find the bid increments for eBay USA here:
http://pages.ebay.com/help/buy/bid-increments.html
If your bid is lower than the required minimum bid it will be rejected by eBay. You will neither be informed about that in an eMail nor will your bid be displayed in the bidders list.
