Yes eggshells are good for roses.
Roses love eggshells when added to the soil they are in.
Eggshells contain calcium and other nutrients that the roses thrive on so by adding eggshells in with the soil around your roses the roses will grow much better and look much better as well.
A lot of other garden plants enjoy eggshells and eggshells also decompose really good and fast in the soil so what you do is break or crush the eggshells up and then mix them in with the soil.
You can also crush eggshells up and mix them with compost or potting soil and a lot of plants and flowers will do very well with eggshells added into their soil.
Eggshells make a good fertilizer for roses as well as many other plants.
Roses also do very well when you add in used coffee grounds to the soil but just don't get any coffee grounds directly on the stem or flowers of the roses as it could cause a burn to it.
But when added into the soil the coffee grounds help the roses grow.