How to safely power a large LED strip project

Canada uses 120V outlets. The amperage of the circuit is typically 15 or 20 amps. But that is at 120V. 12V 5A is provided after the power supply regulates the input down. Without taking into account efficiency, 12V 5A is the same power as 120V 0.5 Amps, or 60 Watts. Add in efficiency costs as no power supply is perfect, it's likely 0.6A input. Look at the label on your supply and it will tell you what the input amperage is. That's the amperage you need to worry about on your power strip/outlet/circuit.

If this is on a small localized display, you should consider using a 200 to 240 Watt 12V supply, like maybe a PC power supply. Less issues with multiple supplies.

The power supplies can each deliver 5 Amps at 12 volts, but they will only draw about 0.5 amps from 120 V, so there is no problem running them all (and more) from a normal 15 Amp 120 Volt outlet.

A power supply or transformer passes power (volts times amps) not just voltage or just current.

In short, yes you can power these from the same outet. You're way under the limit. You need to do some additional math:

Each of your supplies is 5A @ 12V, which is 60W. Assuming 85% efficiency, that means that it draws ~71W from the wall. That's just about 588mA at 120V. All four of your supplies should draw less than 2.5A all together.

To put things in perspective, hairdryers and heaters commonly weigh in at about 1200W (~10A from the outlet). You would need like 17 of your power supplies to start approaching that limit.