Is there a way to apply a 10% discount on all attributes only?

I couldn't find a way to do this so tried applying 10% across the store but only 10% of the starting price was deducted from the attributes

For example: starting price is 8.50 - 10% is 0.85c, Attribute price is 29.95 but discounted price is 29.10 when it should be 26.96

Gill