Welcome, Aji!...thanks for posing an intriguing question. I do find that, while I mean for can't to end in a crisp "T" with my tongue clicking behind my teeth, for some reason it seems to die at the roof of my mouth in a softer tone!
And, I also find, that if I pronounce both words in succession I pronounce a harder "T" if I say can't first...can't/can. The other way...can/can't...the "T" tends to soften and fade. Fascinating! Now these two simple words will never sound the same for me again! And I'm sure I'll be listening to myself say them for weeks! By the way, has anybody read any Kant lately?