Hi Elizabeth,
it would help if you share the table you are using. The totals should always add up, so it is possible that the table you are using is only reporting a subset of the subcategories (example: it gives sub category of only females - so it wouldn't add up unless you add in the male population).
margin of error should be considered in any analysis, but it would not be the cause of the estimates not adding to 100%.
-jami