The easiest way to avoid PMI is by putting 20% down payment; however, PMI can also be avoided if you only have 5% or 10% for the down payment. The way to accomplish this is via a first and second mortgage combination commonly referred to as 80/10/10^s or 80/15/5^s.
These two methods combine a first mortgage lien for 80% of the home price with a second mortgage lien for either 10% or 15% of the home price leaving the remaining 5% or 10% as the down payment. Because the first lien is at the magical 80% loan=to-value, there is no PMI required, even though a second mortgage is being |piggybacked| onto the financing thus allowing for the lessor down payment.
While the second lien terms are not as attractive as first lien rates, the second mortgage is still home mortgage interest and thus deductible as such on your federal tax return where PMI is insurance and offers no deduction.