Welcome to the board. Apparently in the Jamican culture "No" means "No" while "Thanks" is a term associated with "Yes". Saying "No Thanks" is like saying "No Yes" and may make you a percieved soft target for hagglers. Their thoughts are "what is he thanking me for"?![]()
Do yourself a favour and simply say "NO" accompanied with a hand gesture amd/or head shake. It's not considered rude in Jamaica.