Phrases like this are treated like sentences in a text, so you need punctuation. If an editor later wants you to remove it or it gets pulled at the design phase, so what? You don't want them to think you don't proofread. Having the first two lines end with punctuation sets that up for the rest.
If, as happens in poetry, a sentence ran over th line, you wouldn't punctuate that.
Row, row, row your boat
gently down the stream,
merrily ... .