Yep, this is a common issue... check out this threadCould be a faulty sending unit. That is why it isn't registering accurate fuel meter.
My FJ's (2007) gas gauge worked fine when I bought it a couple of years ago, but then encountered the issue. I'm permanently about 1/8th of a tank off now. It still works, until I get down to an 1/8th. I no longer run it down into territory where I know I should need gas. It isn't worth fixing at this point for me.