I need help with a code in javascript that looks if the person has a resale number and if they do if they a discount percentage for sales tax for how much they spend. I am wondering how you can do this in if else statements. If they do not have a resale number it automatically displays sales tax at 6%.

Yes, you can use an if statement. Your logic would be something like this:

If user has resale value
Give discount
Else
Tax is 6%

I hope this helps. If not, could you post your code so we can look at it and give you some pointers?