Under Kennedy I believe the dollar was still backed by an oz of silver.
That changed around 1970.
Rough rule of thumb; money devalues in half every 15 years (quarters in value every 3 decades). So, we're doing a little better thanks to the post 2008 slowdown, since $105 < 20*4*almosttwoish, where almosttwoish=exp(2/3 ln 2)~1.6.
The problem with the official inflation figures isthat things are a little fudged. They are still roughly correct; distorted only enough to remain plausible. The main fudging is done with the hedonic quality adjustment, which adjust the value of modern products pretty much always... upwards. I don't think that should really be so.
Sure $500 laptop now is a few times faster than one you'd have bought 5 years ago; cars now have all sorts of new features over a car bought 10 years ago, and we didn't have "supercomputers" we could carry in our pockets 30 years ago. However the "hedonic quality adjustment" are completely overdone IMO and are completely 'hedonic' in the sense that they seem biased to only act to understate the inflation.
Yet, are there ever 'hedonic' quality adjustments made to reflect the lower quality of produce and goods? 15 years ago you didn't have to worry about your food being lousy GMO produce. 75 years ago you didn't have to worry about GMO nor massive toxic pesticides in your food. Only a few decades ago you wouldn't have to worry that, if you ate meat, whether it was produced by factory farms.
A more accurate method would be to compare 1920s food to organic 2010s food (Organic is generally almost twice the cost of conventional.
And did you have to worry in 1960 that a television or radio you (bought, was made in a sweatshop where people are paid approximately nothing per day, in conditions similar to where iPhones parts were produced by foxconn---suicide nets in the dormatories...)
I guess hedonic adjustments just assume the price of our health and conscience is practically zero.