My battery terminals keep getting A LOT of corrosion building up on them. I sand if off but it just keeps coming back fast, any idea on why it would be doing this and does it matter?

 

Use a battery terminal sealer such as Castle's Long Life.

 

Corrosion on Battery terminals indicates the presense of Sulfuric Acid. It causes the pitted of steel fittings, the blue crystals from any copper and also blisters the wire insulation and can cause a condition called black wire (attacks the conductor).
Only two things can contribute to this.
The Battery leaks around the terminals.
The Battery is being overcharged, and it builds up internal pressure.

You might try a coating of either wheel bearing or white lithium grease once you again clean them.

P