As an interjection thankies
is (hypocoristic|informal|mostly|internet) thank you.
As a noun hankies is
.
thankies
English
Interjection
(
en interjection)
(hypocoristic, informal, mostly, internet) thank you
References
* Usenet newsgroups: [http://groups.google.co.uk/groups/search?q=%22thankies%22&btnG=Search&sitesearch=groups.google.com]