Keyword Density is 4.18% without including more than 4 times the targeted keyword

I assume your tabs link back to your article page and are also on the article page itself - Google will count the keywords in the tabs if they are text links - not graphic text links - it's good to have the keyword in internal links back to your article page because it ads to the target page's relevance to the keyword...

However, if you have ALL (how many?) tabs with the same keyword all pointing to the page, then Google may consider it a bit spammy (think of it this way - how many "real" sites have you seen with the same words in every tab? - none - and Google hasn't either). But you can help your relevance score by being sure that at least one of the 5 occurrences of your keyword is in a header tag ie: <h1>keyword</h1>.

I wouldn't suggest adding any more of the same keyword to the article... but perhaps some words and phrases related to the keyword.

Be careful not to over-use keywords. Google is smart - very smart. A better use of your time might be to get links from other sites with the keyword and similar keywords in the link text pointing back to your article page ie: <a href="yourDomain.com/yourArticle/">Keyword</a>

You can do this a million ways: like article marketing, bookmarking, Facebook, blog commenting (harder to get the keyword in the link), forum posts with your link in the signature, etc. etc.

Good luck... with time, you can do it. It's a long road to real success, but very rewarding - there is no such thing as an instant magical fix.

@ NickL
I have around six tabs pointing to different pages but on the same website. When I use seoquake to know about my keyword density, it shows more than 4% KD

So should I change some of my tabs from targeted keyword (3 word keyord- lon tailed keyword) to LSI keyword or short keyword (2 word keyword or single word keyword)

FACT: Keyword density has never been part of Googles algo.

IMO if you use the same keyword on each tab, Google may find that "unnatural". I suggest you design the navigation to be usable by a human - pretend you want to find some information that is on your site and think of what the tabs should say that lets the user know what information they will find after they click.

If it was my site, I'd probably go with one or two word tabs and make each one different but related.

Again - internal linking is important, but not nearly as much as getting external links back to your site with relevant keywords in the link text (and related text surrounding the link, if possible). Think of each external link from other sites as a "vote" to Google that your site is about what you say its about.

And I agree with jazbo - don't get so caught up in keyword density - just write about the subject naturally, include the keyword in the title tag and in a header tag - if the content is related to the keyword, Google will know it - and if its not, then Google won't show it. Going for high keyword density might and up spammy, get you ranked lower, and turn off your readers - people love the Back button when they encounter keyword stuffed junk - and that does you no good whatsoever.