Not long ago, everything at 99 Cents Only stores cost $.99. Now, very few items can be had for that price.
The value of the Dollar is what has changed, not the value of the goods. The silver value in three 1964 90% silver dimes will still buy a gallon of gas, just like the face value of those same dimes would in 1964. We have a currency whose value floats with the whims of politicians.