Katherine Anne Porter's short story "The Jilting of Granny Weatherall" is the tale of a woman who suffers a terrible situation in her youth: She is jilted at the altar on the day of her wedding day by her groom, George, and is subsequently humiliated as a woman, as a daughter, and as an individual.
This one incident haunts her life until the day of her death when, as she agonizes, she realizes that her entire life has been a sequence of decisions that aim to proof her own value as a person.
You are correct in asking whether she is a static character because the reader can see that she has lived what seems to be a very consistent life. However, it is this very consistency what also makes her a round character because, as she slowly passes away, she realizes what her life has been about: Escaping that one, sad moment.
Granny Weatherall is only static in that we only see her life the way that it is narrated in the present. This, we see through her characterization as a wife, mother, and grandmother. However, if she were completely static as a character she would have totally eradicated the memory of George off her mind, and would have lived in oblivion.
Yet, just when we think that she has, in fact, lived this way, here comes the moment when she arrives at her most important realization of life, which is what makes her a round character as well:
Yes, she had changed her mind after sixty years and she would like to see George. I want you to find George. Find him and be sure to tell him I forgot him. I want him to know I had my husband just the same and my children and my house like any other woman. A good house too and a good husband that I loved and fine children out of him. Better than I had hoped for even. Tell him I was given back everything he took away and more.
To come to terms with something so powerful entails a major change in perspective. This shows that she has certainly changed, even though it is too late. This also shows that her character is much more complex than what we think at the beginning of the story, and that Granny has finally come to a full circle: She has, indeed, lived a life in which she has fought tremendously to undermine what George did once.
Therefore, Granny Weatherall is both a static as well as a round character. The round aspect of her characterization comes when she admits that, even after sixty years, she has battled that one incident in her younger life.