there is no way the IRS will allow people to avoid paying taxes using this trick.
if this really catches up i am sure they will clarify that the determining exchange rate for tax purposes is the median of all inputs or something of that sort.
This is neither a trick nor a method to avoid paying taxes. You would report the same amount of capital gains taxes either way, but this has the potential to significantly simplify accounting for all parties involved.
this requires that my wallet actually has enough bitcoins obtained when the exchange rate was lower.
the mere fact that people need to worry about the issue of reporting capital tax gains when buying things in a store is going to push people out of using bitcoin as money.