Standalone Mini LED Matrix

I would like to build a mini standalone LED matrix as a pressie for my wife (she likes geeky presents) I am going to use a few parts I have lying around to make it. That is, an ATTINY25v and a couple of shift registers to drive a 5x6 LED matrix powered by a 9v battery.

Both the ATTINY and the shift registers have a really wide voltage tolerance (~2v-5.5v) so will I still need to use a voltage regulator? Or can I get away with some resistors.

Thanks in advance.

Just had a random flash back to GCSE technology...
Am I right in thinking that I need to build a voltage divider circuit? Voltage divider - Wikipedia