Hi Lara, also a different technique than that for putting a rounded end on can be to model a sort of rounded cap surface using sweep and then have your main shape extend further such that it collides through the rounded end cap. Then use the End cap to slice off the end of your shape using boolean difference and then apply a fillet around it to smooth out the connection area.
Check out here for some examples of making that kind of rounded end cap using Sweep:
