Hi CrystalMaiden,

Indeed you can use 'avoir tendance à' for 'to tend to' but there is a slight difference between a tendency (une tendance) and a habit (une habitude).

For instance you would say;

"Il a tendance à se répéter" (He tends to repeat himself) rather than "il a l'habitude de se répéter"

or "Ils ont tendance à exagérer leurs compétences" (They tend to overstate their abilities) rather than "ils ont l'habitude .... it's a question of an inclination or a tendancy to do something rather than a habit...

But you will use 'avoir l'habitude de' for things you do most of the time.

"Nous avons l'habitude de nous réveiller très tôt le matin.

(We are in the habit of waking up early in the morning. ) 

I know it's a nuance and probably sounds like nitpicking ....

Hope this helps!