It's there. Hard to believe it wasn't there before (and no one's ever asked, to my knowledge), but I added the rake information in the first beta of 3.2. They can be utilized in the receipt as <rakeN> and <rakeamountN>, where <N> is the rake number, starting at 0. So, if you have 3 rakes defined, the tokens <rake0>, <rakeamount0>, <rake1>, <rakeamount1>, <rake2>, and <rakeamount2>.