No, that's definitely untrue. HPV (human papilloma virus) is only responsible for (off the top of my head so don't quote me and someone please correct me if I'm way off) 40-something percent of cervical cancers, so pap smears are still DEFINITELY necessary no matter what your sexual history is because you can develop cancer of the cervix without having ever been exposed to HPV (which yes, some strains of it are sexually transmitted).
I also hear that certain strains of HPV (although these may not be the ones linked with causing cervical cancer) can be present at birth/from childhood and not cause any symptoms. I'm not sure if this is true, or if it is, whether the virus can be transmitted from one person to another (so again, if anybody knows anything about that please jump in!), but if it is true and it can be transmitted, your partner may not have ever been exposed (through sexual contact with someone else) to HPV and still have it, kwim?
Either way, the first thing is true (about cervical cancer NOT being caused JUST by HPV), so you definitely, definitely need to get pap smears from your late teens onwards regardless of whether you've had sex or not, or had multiple partners or not (or whether your partner has had multiple partners or not). :) HTH!