Just say شكرا
الحمد لله is not a "thank you" equivalent. It means "Thanks God" and in colloquial speech it means "I'm good" or "Things are going well". So you see, it has nothing to do with "thank you".
جزاك الله خير means "May God reward you well". You could use it as a "thank you", but it sounds rather religious and people will probably assume you're a Muslim if you use it alot, because it tends to be used more by the religious people. Unlike common expressions like الحمد لله and ان شاء الله which are used by everybody, جزاك الله خير tends to be used mostly by religious people.