what kind of shop is an a tchibo shop?
Surprisingly I didn’t find any posting about these kind of shops. Neither in this forum nor in the mailinglist. I’d suggest as the main bussines is to sell coffee(beans) to tag them as shop=coffee (didn’t find this in the wiki either). But as they also sell other stuff like fashion, kitchen tools and plenty more (have a look at http://www.tchibo.de) perhaps there is a better definition…
Similar to the german brand ‘Rossman’ i would recommend to tag it as sop=chemist
http://wiki.openstreetmap.org/wiki/Tag:shop%3Dchemist
imo Rossman and Tchibo are totally different …
I dont think its an good idear to tag it that way
Well ok, to me it seem to be similar but your choice is good, too:)
Maybe I have a slightly wrong impression of Tschibo shops 
I would tag a store as “chemist” if it sells mostly “substances” such as cleaning agents, tooth paste, shampoo…, while a “convenience” store mostly sells household “devices” such as knives / spoons / forks, can openers, coffee machines… I guess Tschibo is more like the second, but I might be wrong.