proper Japanese Roma-ji v.s. English spelling

I took a time to communicate with my collegue, who comes from India. I explained some Japanese words to her with letting her know the spellings.In our conversation, she pointed me about the spelling about a word "Sen-su,"which means "fan" in English. She advised me to write like "Sen-soo," because many English speakers would be easier than writing "Sen-su." It is the first time to notice to write under Japanese Roma-ji in explaining Japanese culture or other Japanese issue for foreign people.