When entering a transaction, there is a "Fee" field, but no explanation in the user guide or online help as to how it is treated in the calculations. I have exchange fees in addition to commission, so I assumed this was the place to include those fees. However, if I enter $0.10 into the field when adding a transaction, the transaction register displays it as $0.1017. Is this a bug, or (more likely) am I just not understanding how it's supposed to work? I'm using v9.3.5 (build 375) in trial mode.

Your understanding is correct, the fee is for miscellaneous fees that may be charged in addition to the commission. This can be exchange fees, SEC fees, etc.

However I've never heard of it being off like that. If you enter .10, it should remain .10. I have re-confirmed that this is how it works here, and that it displayed in the transaction register as .10. I'm not sure why it's displaying incorrectly for you, but try editing the transaction to correct it.

I've figured it out. The difference is the exchange amount. The transaction was in a currency other than the display currency.