I wrote something in school about this a few years ago (I was 12 or 13 then, so I don't know how much help this will be...)
My friend and I did a test. We sold muffins on the street (collecting money for a school trip to the prisoner lairs from WWII in Poland) and sold 4 types of muffins.
2 were sold at 5.99 NOK (~ 1 dollar) and the other was sold at 6 NOK. The only coin less than 1 NOK in Norway is 50 øre (0.5 NOK), so unless someone bought 25 muffins (is it called cupcakes in English?), they would be the same price.
Almost all the cupcakes sold were the 5.99 ones.
So then, to double check it, we switched the kinds (the 5.99 ones were now 6, the 6 ones were now 5.99).
Once again, the 5.99 ones sold more than the 6.00 ones.
So it is psycological (of course, this isn't a very good test).
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS