The spelling of the name "Tahnia" can be broken down using IPA phonetic transcription. The first syllable, "tah", can be pronounced as /tɑ/ or /tə/ depending on the speaker's accent. The second syllable, "nia", is pronounced as /niə/ or /niːə/. Therefore, the word can be spelled as either "Tahnia" or "Tahniah" to reflect these variations in pronunciation. Ultimately, the choice of spelling will depend on personal preference and regional accent.