Roblox lowered the minimum price for classic T-shirts to 2 Robux on April 13, 2016, not 5; the 5-Robux floor applies to classic shirts and pants.

What changed

  • Classic T-shirts : 2 Robux minimum.
  • Classic shirts and pants: 5 Robux minimum.
  • This pricing system has been adjusted over time, and Roblox now uses dynamic price floors in the Marketplace.

Why people mention 5

A lot of players mix up “T-shirts” with “shirts,” because both are clothing items but they have different price floors. The 5-Robux number is real, just for classic shirts and pants, while T-shirts are still listed at 2 Robux in the source I found.

Timeline

Item| Minimum price| When it changed
---|---|---
Classic T-shirts| 2 Robux| April 13, 2016 9
Classic shirts| 5 Robux| April 13, 2016 9
Classic pants| 5 Robux| April 13, 2016 9

If you want, I can also explain the difference between Roblox T-shirts, shirts, and layered clothing.