this is pretty much the reason why Bitcoin is not a direct substitute to the fiat. At the moment, Bitcoin usage and level of adoption hasn't gotten to the stage where you can comfortably use it to buy minor item that's  not of a high worth and considering how cheap a pack of condom is and in most cases might be around $1 or $1.5, it's just too unnecessary to even think about using it for such purpose most expecially when you're considering the fact that you will need to consider the extra transaction fee that's involved.

Maybe in the future when Bitcoins level of adoption has risen above how it currently his we can assume that you could make such Purchase but at the moment, buying an item that's worth less than $100 amd choosing to pay with Bitcoin would Make you look like a psycho. Even in my region, some shops won't even allow you pay for a pack of condom using normal bank transfer not to talk paying with Bitcoin when you aren't sure if the person already had some Bitcoin prior to then.