Типа/наподобие/вроде
govern Genitive, which in English can be rationalized through the question of which/what type?
or more literally of the type of what? - of the type of that
, also mind that in combination with что-то
- такого
is a Genitive of такОЕ
and not of такОЙ
, and instead of типа такого
you can also say такого типа
where такого
refers to the тип
which translates as of such type
into English.
That said, типа такой/ая/ое/ие
(and in other inflexions required by the predicate) is also a valid combination, applicable in interrogative sentences where a speaker asks about a kind of something, but in this case типа
is a rather slangy filler word or a slang variant of the normal вроде/наподобие + Genitive
pretty low in register, e.g.
- (a punter) Мне нужен портфель such and such
- (a salesman showing a briefcase) Типа такой?
And as a follow up... Он типа такой крутой полицейский. -- This is
where the confusion comes in. Shouldn't this then be "типа такого"?
The chosen case conditions the meaning, in Nominative it expresses sarcasm, whereas in Genitive it's a straightforward expression of semblance to something with no hidden agenda. It could be that in the policeman sentence the case wasn't chosen very carefully if it meant to express just semblance. Admittedly in practice some overlap may occur in use of both cases but the first meaning i get reading the policeman sentence is sarcasm.
типа такой
(or justтипа
) is very similar to the current British usage oflike
in a casual speech (mostly, by youngsters): "And I, like, wha'?" == "И я типа такой - чо?" etc. :)