The deal is, the 5 amp fuse is sized to protect the instrument cluster only, and with your radio stealing power from the dash, the fuse blows because at higher volumes, the radio plus instruments consumes more than 5 amps.
Putting in a larger fuse is a very bad idea, as it would no longer protect the instruments, in the worst case the oversized fuse would allow an electrical short in the instrument cluster with the radio turned off to start a fire behind the dash.
The correct answer is to run a new wire all the way to the battery (+) connection, with an inline fuse to protect the radio. Chances are good that the radio wiring harness had that fuse in it already - it is up to you to route the wire to someplace where you could check and replace that fuse.
If you MUST steal power from inside the Jeep, steal it from something else like the lighter socket, which has power to spare and a 20A fuse. But it's a bad idea, since either the lighter or radio could blow the fuse, and if you were playing the radio loud and then pushed the lighter in, the fuse would blow. That is the whole idea with fuses, normal current doesn't blow the fuse, extra current draw does.