Fixed number rounding in `NP.VAT()` in use 0% VAT

[tomee03]

var n1 = 10.948283; var n2 = 0.43333421; var n3 = 5;

console.log(n1.VAT(0, 2)); console.log(n2.VAT(20, 2)); console.log(n3.VAT(20, 2));

// New 10.95 0.36 4.17

// Old 10.948283 0.36 4.17