Do roasted almonds have similar calcium value to raw ones?
Looking at the USDA database, roasting the almonds does not affect the calcium levels (comparing equivalent weights).  Look at the value per 100g or value per ounce rather than volume-based values and you'll see what I mean.

Raw almonds average 269mg of calcium per 100g (or 76mg per ounce).

https://ndb.nal.usda.gov/ndb/foods/show/3635

Dry roasted almonds average 268mg of calcium per 100g (also 76mg per ounce).

https://ndb.nal.usda.gov/ndb/foods/show/3637