From the Washington Post: Judge Says Currency Shortchanges the Blind:
A federal judge said yesterday that by keeping all U.S. currency the same size and texture, the government has denied blind people meaningful access to money.
Government attorneys argued that forcing the Treasury Department to change the size or texture of the bills would make it harder to prevent counterfeiting.
Robertson was not swayed. “The fact that each of these features is currently used in other currencies suggests that, at least on the face of things, such accommodations are reasonable,” he wrote.
A charming non-answer to a FAQ on the subject from the US Treasury:
QUESTION: I believe that the Treasury Department should add braille markings to our currency to help the visually impaired. Are there any plans to do this?
ANSWER: You may be aware that over the years, the Congress considered several legislative initiatives to incorporate such features in United States currency. However, it never enacted any of them into law. Also, our Bureau of Engraving and Printing (BEP) has conducted several reviews in the past of our currency system. They evaluated the incorporation of Braille symbols and/or other design features into currency to help the visually impaired.
We understand that the National Academy of Sciences and the Committee on Currency Features for the Visually Impaired have also studied this question. In these studies, individuals evaluated features that could be incorporated in the production of United States currency notes that would enable blind and visually disabled people to more easily determine the denomination of a note. Previous studies surrounding this issue suggested that several modifications were possible, including Braille dots, raised symbols, cutting corners, producing notes of different sizes, or with perforations. The studies have shown that the durability of these modifications is limited. Research into features to help the blind will continue.
You may be interested to know that the Series 1996 $50, $20, $10 and $5 currency notes include a large dark numeral on the back of the note that will help millions of people with low vision to identify the denomination of their currency.