On some occasions, the fee gets too high because of dust. Which I do not want. And now I would like to hard code a limit into bitocoind (bitcoincore) to reject a (per RPC transmitted) transaction IF the internally calculated fee is above a limit like: 0.01 BTC.
In the current codebase any transaction will be rejected if the transaction is >100k. 100kB times the base fee for non-free transactions is 0.001, so unless you've increased your fees there is already a hard limit ten times lower than you asked for.