Master Alchemists perfected Alchemist's fire

[Zanniej]

The description:

Alchemical Fire Mastery
Type of Feat: Class
Prerequisites: Master Alchemist 3
Specifics: Once per day the Master Alchemist may create a number of perfected alchemical fire grenades equal to half of his master alchemist levels. These cost 150 gp per grenade.
Use: Selected

The question: Is that half his levels rounded up, or down?

[Zanniej]

Good to know, thank you!