I can't resist adding that, although Neil's reply is perfect for Paris, it would not be quite right in Marseille. In the whole of the large region known as the Languedoc (originally "the language of oc") these words would sound almost as though they ended in -ng.
Yes, this absolutely true -- for simplicity, the situation I am describing is what may be regarded as a "standard" pronunciation and is generally what I'd advise learners to follow unless you've some particular reason not to. But it's true there are some key dialectal differences.
In Midi French, word-finally, nasalised vowels also tend to be followed by a sound similar to English "ng" as you mention. Word-internally, this "ng" consonant tends to become whatever nasal consonant is closer to the following consonant. So for example, in the word simple, a Midi speaker would pronounce the m actually as a [m] sound. There are also differences in the quality of the vowels-- e.g. in this word, the vowel written i is cloesr to a nasalised 'e' vowel than is nowadays the case in Standard French.
There are also some differences in Canadian French (notably, the nasalised vowels in closed syllables tend to be diphthongised, and again, there are more genearlly some quality differences in the vowels as you might expect).