FIX the AUCTION HOUSE!!!!

[Shioban]

You need to undercut by the tax so your item is cheapest regradless of tax. So it selll 1st. ya that may not be 2k but still 4700 wouldn't be a bad undercut.

No, you're missing the point.

When you list your price for 1G or less, it becomes the top listing.
People will look at a list such as this, and go "I want X Quantity of these", therefore will always purchase the cheapest one closest to that quantity;

The retainer with the lowest price, will always appear first, even if that's by 1G.

THAT'S the reason undercutting exists, taxes play no part in it.