I'm sure Amazon is constantly adjusting their prices in order to maximize their sales and revenue; they even have some price automation tools as part of their inventory management system for people who sell their stuff through Amazon.
However I'm not sure these adjustments are meant to make people perceive that Amazon has the lowest prices. Instead it seems like they're meant to ensure that Amazon actually has the lowest prices on the most popular and high volume items. On those items they are pricing for high volume, while on the lower volume items they need a higher price to get an equivalent margin. That's what this looks like to me: maximizing margins across products with different sales volumes.
However I'm not sure these adjustments are meant to make people perceive that Amazon has the lowest prices. Instead it seems like they're meant to ensure that Amazon actually has the lowest prices on the most popular and high volume items. On those items they are pricing for high volume, while on the lower volume items they need a higher price to get an equivalent margin. That's what this looks like to me: maximizing margins across products with different sales volumes.