There's a cool 1990s magazine scan that breaks down the margins for an SNES cartridge: https://www.reddit.com/r/gaming/comments/11140t0/pricebreakd...
33.1%: Nintendo's charge
29.8%: Retailer's margin
15.1%: Publisher's margin
14.8%: VAT
That's... 92.8%.
Developer's royalty: 4.6%
"Yikes" -me, just now