Ever, as an indefinite time adverb, means at any time. When it is used with the present perfect or present perfect continuous, it means at any time up to the present. This is a very common usage and your examples of use are absolutely fine, Margot. Compare also the following:

• Have you ever seen the Queen in person? ~ No, I never have.
  
• Have your ever grown vegetables in your garden? ~ I did a few years ago, but not recently.

ever - at any time in a period in the past

We can also use ever to enquire about a particular period in the past and this usage, while less common, requires the past simple:

• When you were living in Egypt, did you ever see a Nile crocodile? ~ No, I don't ever remember seeing a crocodile in the Nile!
  
  
• Did you ever sail up the Nile? ~ Once, but only from Luxor to Aswan.

ever - at any time in the future

Note that ever is also often used with going to and will future forms when predicting the future:

• Is he ever going to give up gambling and live a normal life? ~ No, I don't think he ever will. ~ Do you think they'll ever get married? ~ I don't think they'll ever have enough money.
  

Yet and already

Note that yet, meaning up till now, and already, meaning earlier than expected, are also indefinite time adverbs like ever and are associated particularly with the present perfect tense and the verb be. Like ever, yet is used mainly in interrogative and negative sentences:

• Is the mail here yet? ~ No the postman hasn't come yet.
  
• Are you going to stay? ~ I don't know yet. No decision has yet been made.
  
• Have the children returned yet? ~ Susan's already here, but Simon hasn't come back yet
  
• He's already earned enough money to retire on and he's only thirty five.
  
• It's already nine thirty and I'm already late for my appointment.

in the last ten years / six months / three weeks / few days

These adverbial expressions indicate a fixed period of time, and say when something happened. They connect the past with the present and, like ever, since and for are most commonly used with the present perfect. Your supermarket example therefore sounds best with the present perfect passive, Bea, rather than past simple passive:

• In the last ten years, since 1993, a lot of supermarkets have been built on the outskirts of towns and in the next five years many more will be.
  
  
• He's on hunger strike and hasn't eaten anything in the last three weeks. For three weeks now, he's eaten nothing at all
  I haven't spoken to Roger for months / in months. He must be out of the country.
  
  
• In the last few days I've tidied my study and thoroughly cleaned the house.