Change divisions on colour bar

I have a contourf plot with N ammount of bands. No matter how many bands i have in the contour plot i have a smooth slowly changing color bar, even if i only have very few colour bands? How can i set the colourbar to have the same ammount of bands with ticks on the band boundaries.

e.g if i have my z variable 100:20:200 and my contourf matching that with 5 bands. How can i make my colour bar have 5 bands with the ticks [100,120,140,160,180,200]?

Thank you for any help with this.

[Walter Roberson]

Which MATLAB release? colorbar() changed implementation a lot as of R2014b.