Explanation: Roman tariffs actually varied - the standard transport tax within the Empire, the portaria, was 1/40th (2.5%), payable once at a local administrative center (typically a large city). There was a special import tax placed on the East, though, the tetarte, which was 1/4 (25%), mostly to take advantage of the high-value spices, silks, and incense that poured over the Eastern borders. By some estimates, the tetarte provided up to a third of the Empire’s tax revenues! Which demonstrates both the value of the luxuries being imported, and the relatively low costs taken by the central government of the Empire.

An amphora of garum is fine too. Specially if you’re from Hispania; their garum sociorum (lit. “garum of the allies”) was specially cherished.