This is in addition to the 50 training packages the company had previously announced.
The greatly expanded offer is in response to high demand from retailers.
Winners of the competition will receive course materials for the BTEC Level 2 Award in Under Age Sales Prevention for each of their staff, worth £100 each.
They will also receive training from a former Trading Standards Officer at Under Age Sales Ltd, who will prepare staff for the exam at a mutually convenient time.
The officer will supervise them in taking the exam, before marking it and posting it to Edexcel for the qualification. The training qualification on offer is recognised by Trading Standards, the police and local authorities.
To enter, retailers simply need to log on to jtiadvance.co.uk before November 25 and take part in a short quiz. Their details will then be entered into a prize draw.
Retailers not already registered on JTI’s trade website should speak to their JTI representative or call JTI’s Customer Careline on 0800 163 503 to receive a Contact ID.
Tom Hirons, government relations manager at JTI, said: “We all agree that children should not smoke and should not have access to tobacco products.
“Offering retailers this qualification is part of our wider commitment to supporting retailers in making sure that under 18s cannot buy tobacco in their stores. Retailers should take advantage of this opportunity to win high-quality training for their staff and protect their businesses.”