Is the Hebrew word ta'arif תעריף related to the English word "tariff"? Well, of course it is. Not only do they have the same meaning, but the Hebrew actually derived from the English (or one of the European counterparts - French tarif, Italian tariffa, Spanish tarifa).
The English word tariff, however, does have Semitic roots. It comes from Arabic:
from It. tariffa, M.L. tarifa "list of prices, book of rates," from Arabic ta'rif "information, notification, inventory of fees to be paid," verbal noun from arafa "to make known."
When I first saw this, I thought - hey, maybe it's related to the Hebrew word oref עורף, meaning "neck", or the root ערף meaning "to drip" (and the source of arafel ערפל - cloud, fog). But one of the advantages of my acquiring Stahl's Arabic etymological dictionary is that I don't have to guess. And he clearly states that there is an Arabic root ערף meaning "to know".
Stahl doesn't connect the Arabic ערף to either of the Hebrew roots, and I imagine that if he could have, he would have. He does, however, mention that in Medieval Hebrew, ma'aruf מערוף meant "customer, clientele", from the Arabic root. In modern Hebrew slang, ma'aruf means "a favor", as in "do me a favor". This meaning is also taken from Arabic, and Stahl suggests that the development might have been from "to know" to "befriend" to "do a favor".