Can catalog price rule and shopping cart price rule work at the same time?

[imfionalin]

I'm trying to start a promotion on our store:

10% off all items

Buy $500+ 15% off on everything

Buy $700+ 20%off on everything

I've set up the three rules already, but for example when the total reaches more than $500 it will apply 10% off and then 15%off which is not what I wanted. It seems that it can't cancel the 10% off discount once the total reaches $500 +

Can anyone help? Thanks

[Tom Robertshaw]

I think if you have multiple rules with the same name and different priorities you can set the one for the larger discount to "Stop all other rules from processing". 

Alternatively, instead of having one that gives 15% and one that gives 20%. If they both are trigger, just make the 20% give a 5.88% discount and it'll work out to be the same as giving 20% discount.