A fare from the US with 300$ taxes and charges... uhmmm
Sounds like a european carrier that rips you off with fuel surcharges !
Since there was no recent mistake fare of LH or BA my assumptions are you talk about AF to FCO?
Now especially because they are european they should have to comply with the tax refund ! I dont know about fuel surcharges but usually you get everything back. Thats what I love on my 3$ Lufthansa tickets to ZRH