Tacos and Beyond

Here's what I learned in elementary school: When you're talking about money, the dollar and cent symbols go in different places next to the numbers. The cent symbol goes after the number. The dollar symbol goes before the number. For example, if something costs 99 cents, you would put either 99¢ or $.99
Imagine my surprise then, when we moved to our current home, we saw a local taco place waving their sign next to the road

and a few months later, they had banners to advertise.

This went on for years. They even got a new sign for waving next to the road.

Have I been mistaken all these years or is this just a new way of doing dollars and cents I didn't know about?