It doesn't have to do with dollars or pesos, you close a deal on a house and make two contracts, one with the value you are buying it for, a contract for you an the seller, and another one that you will use for putting the house on your name, for a lower amount to pay less transfer tax and if possible avoid IVI tax every year (I think the threshold is 5,000,000 pesos , below that you don't pay yearly iVI tax. The best is to check the current value of the house according to IVI and make a reasonable appraisal.
I have been thinking if I have moral problems if I would do this, but in view of how taxes are stolen here, I wouldn't feel guilty.