Textbox tabsindex

Hi,
I have a question on tabindex...
I am using 5 textboxex in my design page. i added tabindex as 1,2,345.....
when i entered data(number with decimal value  i.e.,  2212.33) in third textbox and when i press the tab the curser is coming to the start position of same  textbox and next tab position it is moving to next textbox. Can anybody help me.