I don't know what they teach in English these days, but back in my day (hahahahaha, back in my day, as if I'm sooo old, but to someone younger than 60, I suppose I am), I was initially taught the series (or serial or Oxford, if you prefer) comma. That's the one where you place a comma before the conjunction: red, white, and blue.
That all changed in 10th grade. The English teachers, as well as the journalism instructor, were marking me off for following the series comma rule and demanding that I drop the comma before the conjunction: red, white and blue. Me, being a sheep, followed suit. From day one, I thought a series without the comma before the conjunction looked rather naked and the intention of the sentence was insincere.
Flash forward with me to my late 20s. Behold: I am now working at my dream job—an assistant editor for an independent educational book publisher of supplementary materials for special education teenagers. The house style for a series was the serial comma rule. Hurrah! I received my best training as a writer and editor at that job, thanks to Winnifred, my supervisor.
Today, I only withhold that last comma in a series if a publisher's house style calls for it or if I'm writing a press release. How about you? Do you put in that final comma in a series?