"We really need to implement some policies and this is some more information around one of those policies that perhaps tobacco is not as important to small convenience stores as previously thought."
Tobacco manufacturers have long argued the product drives significant foot traffic into stores.
They also believe those who buy tobacco spend almost twice as much on additional products as non-tobacco-buying customers, she said.
"This outcome doesn't support industry claims that tobacco is an important driver of add-on sales at convenience stores," Dr Marsh said.
Customers who bought tobacco and non-tobacco items spent on average $6.99 on non-tobacco items, while customers who bought non-tobacco items only spent on average $5.07.
The most common purchases were food, such as takeaways, fruit, ice creams, pies and lollies