If you enter a price higher than 16,777,216 EC, the Exchange interface will round it when you post the item for sale. In the examples below, the original price I entered is on the left and the price to which it was rounded is on the right.
The exchange as it is is a poorly coded element of the game at best. The filters are laughable and ineffective, searching only for exact words rather than variables using Regular Expressions and best-bet results.
Apart from that, inflation makes anything in the last 3 numbers of any value a decimal (to me, anything that costs 100,000 EC is the equivalent of 100 points, 200,000 = 200 Points, 200,111 = 200 points).
The exchange has needed a re-work of the code since day one, and this was even admitted by a dev at one point (saying something like "the exchange code is a mess... would probably be easier to just re-do the exchange, rather than fixing it).
A minor issue like this really dosen't make that much of a difference.