Internet is Beautiful

https://en.wikipedia.org/wiki/Variety_store#North_America

Frank Winfield Woolworth had seen the success in Michigan and western New York of so-called nickel stores, where everything cost five cents (a nickel). On February 22, 1879, Woolworth opened his Great Five Cent Store in Utica, New York, which created the American institution of the "five and dime", and became the F. W. Woolworth Company.

There were many names for this type of store:

• five and ten cent store, five and ten, five and dime (a dime is the name of a US ten-cent coin).[26]
• dime store
• 5, 10 & 25c stores[27]
• five cent to one dollar stores[28]

I don't see any record of the first nickel store, and it sounds like Woolworth's wasn't quite the first. But if we use 1879 as our baseline:

https://www.in2013dollars.com/us/inflation/1879

That's a 3,139.76% price change due to inflation to 2025.

So a nickel store in 1879 would be a $1.57 store in 2025.

I don't know if Dollar General was the first "dollar store" in the US, but it sounds like it was early:

https://en.wikipedia.org/wiki/Dollar_General

In 1955, Cal Turner developed his idea of a retail store selling goods for a dollar, based on the Dollar Days promotions held at other department stores, by converting Turner's Department Store in Springfield, Kentucky, into the first Dollar General Store.

A dollar store from 1955 would be a $12.09 store in 2025.