Why does Sakura's inner voice say "cha" at the end of her sentences?
According to Catchphrases and Verbal Tics from Naruto Wikia, the phrase "Cha" was replacement of "Shannarō" and "Shannarōyo" in the English dub often used by Inner Sakura, which have no literal meaning, but it can be translated into "Hell yeah!", "Hell no!", or "Damn it!" depending on the situation.