roughly vs just about

roughly and just about both are adverbs.

Word	Noun	Adjective	Verb	Adverb
roughly	No	No	No	Yes
just about	No	No	No	Yes

As adverbs, roughly and just about are synonyms defined as:

roughly and just about: (of quantities) imprecise but fairly close to correct

Other synonyms of roughly include about, approximately, around, close to, more or less, or so, some.

roughly (adverb)	just about (adverb)
(of quantities) imprecise but fairly close to correct	(of quantities) imprecise but fairly close to correct
with rough motion as over a rough surface
with roughness or violence (`rough' is an informal variant for `roughly')