send and receive HEX over TTL

On the serial monitor I get back some ASCII code.

Why are you sending binary data to a device that expects ASCII data?

I want to save all 5 bytes in a variable

Of what type? And why? Specifically, why not just send that data in the first place?

To read the 5 incoming bytes (0x0F, 0xBB, 0x06, 0x00, 0x00) I could use this code:

You need more than that, but that's the significant statement. So, what is the problem?