Could you explain what exactly it is that you are doing on the bench press?
What machine are you using,
what weight are you using
how many sets and reps are you completing
What form are you using (ie. Hand spacing, grip, foot position - picture is helpful).
Also, how long have you been training, and mention which exercises you do specifically. How many days a week do you train?
You mentioned you have rounding of the shoulders, do you do any Back exercises?
When you mention 'feel', are you speaking of DOMS - Delayed Onset Muscle Soreness which is the discomfort that comes on after about 24-48 hrs within the muscle group, or do you not feel anything as you do the movement?
If you can provide the above information that will definitely help to make an assessment of your problem.
Cheers