Most HC-05 boards are mounted on top of a slightly bigger board that already has the required 3.3volt regulator, indicator LED, etc. If the board has 4-6 pins on one side, and 3.6-6volt is written on the back, then you can (must) connect the power pin of the module directly to 5volt. The RX pin however must be stepped down with a divider (1k:2k) if you connect it to a 5volt Arduino.
Leo..