tally vs sum up

tally is a noun but sum up is not a noun.

Word	Noun	Adjective	Verb	Adverb
tally	Yes	No	Yes	No
sum up	No	No	Yes	No

As verbs, tally and sum up are synonyms defined as:

Other synonyms of tally include add, add together, add up, sum, summate, tot, tot up, total, tote up.

tally (noun)	sum up (noun)
the act of counting; reciting numbers in ascending order
a score in baseball made by a runner touching all four bases safely
a bill for an amount due

tally (verb)	sum up (verb)
determine the sum of	give a summary (of)
keep score, as in games	determine the sum of
gain points in a game	be a summary of
be compatible, similar or consistent; coincide in their characteristics