How do I figure out the sales tax in NJ

How do I calculate sales tax on a car for NJ is it on the whole car or on payments × term ?

6.625 % on payments also .4% on gas guzzler 19mpg or less combined EPA or greater than $45k

What about for NY? Thank you for your help!

Whatever the tax rate is x total lease payments. Due upfront but can be rolled in

It varies by county. If you google it you will find the official NYS page that tells you your rate.