Price Changes Incorrectly when Product moves to Cart

[johnb804]

My Prestacart has been coming together really well. But this evening, items with attributes are showing incorrect prices when added to the cart.

Items without attributes are fine when added to the cart, as are the first attribute prices. But the second attribute price shows correctly initially and then when added to the cart, the price changes to an amount unrelated to any other calculation.

The price in the cart is still showing tax excluded and the price change doesn't fit a tax. For example, what starts as $19.95, when added to the cart becomes $20.19, for no apparent reason. $24.95 becomes $26.85.

Any help with this will be appreciated.