The answer is, in fact, &quot;because everybody else does it&quot;.<p><a href="https:&#x2F;&#x2F;www.chrisstucchio.com&#x2F;blog&#x2F;2012&#x2F;hft_apology2.html" rel="nofollow">https:&#x2F;&#x2F;www.chrisstucchio.com&#x2F;blog&#x2F;2012&#x2F;hft_apology2.html</a><p>This can be partially fixed with a very technocratic market microstructure change (eliminating the subpenny rule). But politically that&#x27;s very much a &quot;huh?&quot; point - imagine Bernie Sanders saying &quot;I believe we should let traders quote in increments of 1&#x2F;100 of a cent, not 1 cent&quot;.<p><a href="https:&#x2F;&#x2F;www.chrisstucchio.com&#x2F;blog&#x2F;2012&#x2F;hft_whats_broken.html" rel="nofollow">https:&#x2F;&#x2F;www.chrisstucchio.com&#x2F;blog&#x2F;2012&#x2F;hft_whats_broken.htm...</a><p>(This would fix things on the placing orders side, but not on the cancelling orders side.)