I said I'd replay when I knew more in the comment above, so better late than never:
RingCT transactions currently clock at about 13 kB for 2 inputs and 2 outputs at mixin 3. Only one output can get it down to about 6 kB, but typically change means 2 outputs will be the usual case (for now). Most of this can be pruned at some point, but that's still the size which is considered for the fee.
Fees were recently decreased from 0.01 monero/kB to 0.002 monero/kB (80% decrease). The fee for a 13 kB ringCT transaction will thus be 0.026 monero (vs the 0.13 it would have been without the fee change).
It is expected that fees will follow a dynamic formula based on block size at some point in the future, but this is not done.