Of course it matters.
When you apply for jobs you submit a resume. At this point, your resume is the only thing these companies have to compare you against other candidates. The only important things on your resume are GPA, work experience, extra-curricular activities, and skills. If you are smart and networked like you should have (starting freshman year), then you will be given extra consideration.
Almost all job postings have a minimum GPA. You NEED to make the minimum GPA and anything above that will help put you above other candidates. You can not imagine how competitive the job market is, and having a GPA advantage is necessary for first round interviews.
A lot of companies often recruit by school so therefore your GPA is compared to your classmates, not other schools. This means you're school name is only important in getting the company to look at your resume and that you better have a good GPA relative to your classmates.
GPA is not helpful after getting a first round interview. To get a first round interview you need to meet the minimum requirements. For interviews, they will compare candidates based on their knowledge and how they come across in the interview. Work experience, leadership positions, knowledge from classes, etc will come up in an interview and will put you above other candidates but your GPA number pretty much does not matter at this point.
Most importantly, if you can get a summer internship after your junior year, then you have a great chance at being hired at that company for full time. When applying for these summer internships, companies will only see your GPA from freshman and sophomore year. After you get the internship and then the job you can slack off hardcore since you don't need your GPA to get a job anymore.
So bust your ass and take easy classes freshman and sophomore year to boost your GPA as high as possible and then after you lock down an internship, you can slack off and take your harder classes junior and senior year.
You also need to start networking and acquiring leadership positions.
PM me if you have any questions.