I dont have NOC with me. Can i pay road tax in Bangalore ?

For paying road tax in Bangalore, you don't need NOC. NOC is needed only for Vehicle reregistration and ownership transfer.

You can calculate road tax in Bangalore below.

Road tax to be paid in Bangalore for outside state vehicle

Step by step instruction  for road tax is provided below.

• Find the nearest RTO as per your residential zone. Bangalore is divided into multiple zones and every zone has dedicated RTO. 
• Calculate the tax amount:  Road Tax or Life Time Tax (LTT) is calculated based on the price of the vehicle,age of vehicle and its cubic capacity. Life time of vehicle is assumed to be 15 years, so older your vehicle, lesser LTT you need to pay. Usually, it is around 10% of the price of the vehicle. Visit the counter where this calculation is done and get to know the tax to be paid
• Fill the FORM 14 (KMV-T14). This form is required for paying road tax. The Original Invoice should be accompanied with this. Form is available at http://tesz.in/ApplicationForm/kmvt-14.pdf
• After this, deposit the required amount in the cash counter. If tax is less than INR 3000, payment can be made over the counter. If tax is more than INR 3000, a demand draft for the tax amount needs to be paid in favor of RTO.