Discount value rounding up
I have a dynamic percentage value that is being used when a coupon code is being entered.
Once the coupon has been accepted it creates a session variable of 0.whatever and this figure is used in the eCart Discount section when multiplying the cart's sub total by the value held in the session variable.
I seem to be struggling with rounding. For example, I have a product in the cart of £299.00. When I apply the 10% discount code it discounts £30 and not £29.
Is there anything I can do easily to ensure the correct value is passed?