I'm fairly certain that the Artisan science building cost reduction causes a display error because the building costs are rounded and decimalized...but the actual cost VS the cost displayed are different.

e.g. Here is my Artisan science.

Artisan 20,510 -5.1% Construction Time & -5.1% Construction & Raze Cost

Building cost for a building is 804 gc

However, when I build a building, it takes away 805 gc.

Can be problematic when making calculations beforehand, only to find out that the costs were higher than expected.