Indentation rhymes with:
instrumentation, argumentation, augmentation, confrontation, disorientation, documentation, experimentation, fermentation, fragmentation, implantation, implementation, incantation, instrumentation, misrepresentation, orientation, ornamentation, ostentation, pigmentation, plantation, presentation, recantation, regimentation, representation, sedimentation, segmentation, transplantation
Indentation sounds like:
inattention, intention, intimation, intimidation, intonation