I can't speak about the ebook-buying public in general. I haven't bought many ebooks yet, but I used to be more willing to buy paperbacks by authors new to me when they were $4.99, $5.99, $6.99.
That said, I think it's every author's ambition to sell books for what the author thinks they're worth, not solely what might be an attractive price to buyers.
I may be alone on this, but if a more realistic, higher price is one's ultimate goal, I prefer the books be priced realistically from the beginning and not jump. As a buyer in a sea of 99-cent books, sometimes I am inclined to think a higher-priced book is of superior quality anyway.
Personally, I've priced my ebooks from 99 cents to $2.99. The 99-cent books contain three short stories each. I also have a $1.99 book of 24 poems, and I've published a $2.99 book of 32 poems, many by well-known authors. I think I've priced each book realistically and fairly based on amount of content.