Dear Sir
The real position is as under :-
1) When you sell interstate to another registered dealer & if he provides C form for the transaction, you can charge CST @ 2%. In your case, since you are selling to a end consumer, Form C is not applicable and hence question of C form does not arise and 2% tax is not applicable to you.
2) In case of inter state sale to other than registered dealers, the CST to be charged is the rate at which it is charged when the same product is sold within state. (i.e) if you charge 4% tax for the product when you sell within the state, you need to charge 4%. If you charge 14.5% for the product when you sell the same product within the state, you need to charge 14.5%.
Hope this clarifies your doubt.