In Wolfram Warptangent (Monero v0.10), a new fee structure was introduced, in addition to decreasing the minimum tx fee. What is the current fee structure?
Two weeks after the v3 fork, nominal fees will decrease from 0.01 monero/kB to 0.002 monero/kB. At the same time, the fee multipliers used for priority determination will change from x1, x2, x3 to x1, x20, x166. These numbers are chosen so that using x166 compensates a miner for the loss of block reward incurred by pushing the block size substantially over the median of the last N blocks. In simplewallet, those extra fee tiers are selected with
set priority X, with X from 1 to 3, and those will map to the above multipliers for all subsequent transactions.