I don't see how your numbers add up though. Take this example:
An item starts at 99 cents and sells for $25.00
Listing fee was 20 cents and final value fee was $1.31 for a
total fee of $1.51
Listing fee now is 15 cents and final value fee is $2.19 for a
total fee of $2.34 for a price increase of 55%
The difference between $1.51 and $2.34 is not 6 cents.