It's really about 20%
Yes, the real rate using the original calculation method is well over 20%. In 5 years the purchasing power of your money halves, and you get to pay tax on the fake gains of the devaluation
Groceries are odd. At the big box grocery store some things have gone up alot and some only a little. For example, the coffee I used to buy there has nearly doubled in price, but if I buy it at ALDI or Trader Joe's, it's only about a dollar more than it was a year ago. Canned goods, the price difference is not noticeable. Meat prices are insane everywhere unless you catch a sale. Produce is hit or miss. Some things like melons are about the same as they are every summer, but citrus is really expensive. Tomatoes, Onions, Cabbage, Potato....may have gone up, i dont remember the exact price a year ago, but not noticeably.
There is more than one way to make you pay more. They can raise the prices or keep them the same ... and just change the packaging so the qty you get goes down for the same price, often so it's not too obvious unless you carefully compare like-for-like. Bigger stores can dictate suppliers do this.
Everything at every store got their via transportation, and with energy prices up that means prices will be higher one way or another.