0.1uF ceramic for high frequency current switching support. No figuring needed.
10uF electrolytic in parallel for higher current surges wouldn't hurt on large LED driver chips like this, or MAX7219:
Supply Bypassing and Wiring
To minimize power-supply ripple due to the peak digit driver currents, connect a 10?F electrolytic and a 0.1?F ceramic capacitor between V+ and GND as close to the device as possible. The MAX7219/MAX7221 should be placed in close proximity to the LED display, and connections should be kept as short as possible to minimize the effects of wiring inductance and electromagnetic interference. Also, both GND pins must be connected to ground.