'One answer, as outlined by VanRullen and Koch (2003), is that continuous representation “cannot satisfactorily account for a large body of psychophysical data”. For example, 1 cent does not typically have much value to most people. However, a person may decide to buy a product if priced at $1.99 – yet, refuse to buy the same product if priced 1 cent higher at $2.00. Such an abrupt (or step) change in the brain’s purchasing decision cannot be modeled using a continuous representation despite extensive attempts to do so (Basu, 1997).'

The tacit assumption made here seems to be that our concept of number is hard-coded into our brains at the physical signal level, and so that when we think of the number 2, some part of our brain generates a physical signal that has the quantity of 2 (absent that assumption, why would one think that this experiment tells us anything about how signals are physically encoded in the brain?)

AFAIK, it is generally thought that our concept of numbers is at a more abstract, symbol-manipulation level (especially when, as in this example, fractions are involved.) It seems to me that this paradox (which looks like a variant of the sorites paradox, e.g. what is the minimum size of a heap of sand?) is resolved if we consider peoples' tendency to disregard the pennies in a monetary amount.

Caveat / mea culpa: I have not read the papers referenced in the quote.