A well-kept secret for closing the sale
Don't worry about closing the sale. Instead, focus on making an authentic connection with your customer -- asking quality questions about their work, their needs and their life. This will open the door for you to talk about your product.
Source: Sales trainer/coach Doug Stewart
Once they trust you and believe you have their best interests in mind, they will buy from you if you have a product that will in fact meet their needs. All you will need to do is ask. You won't need the "101 best closing lines" book.
If you do the opening right, if you care, if you are authentic, you won't need to close. Your customer will do it for you.