IronQueen, if you're worried about any ramifications if you try to talk to your manager about this, consider contacting your closest ADA office. Sometimes a simple phone call there can help take care of matters. They may be able to contact your employer and find out what's going on and straighten out matters. An advantage to this is that once the ADA office contacts your employer, your employer will take steps to make sure nothing happens to your job because they're well aware that outside forces are looking into this. I get the feeling you may live in a smaller town or work in a smaller grocery store hence why you're getting this behavior from your manager, and it's entirely inappropriate of her to treat you in this manner.
(I'm speaking from experience -- my ex-husband was refused a TTY at work years ago. He contacted the ADA offices (in St. Paul, MN) and they made some phone calls to his employer to find out what the situation was, and they all got it resolved. It was quite quick and handled professionally.)
