For electronic filing, the IRS requires all amounts that are transmitted individually to be rounded (50 cents or more rounding up to the next dollar, and 49 cents or less rounding down). Since each line of the Schedule B is transmitted for electronic filing, each amount from Form 1099-DIV, Box 1a gets rounded individually since it is listed on Schedule B individually.
The IRS Instructions for Form 1040, page 21, states that if you are adding up multiple amounts to enter on one line of a schedule or a form, you should add the amounts and then round the total. Since the qualified dividends amount on Line 9b of Form 1040 is listed only as a total, TaxAct® adds the amounts from Form 1099-DIV, Box 1b and then rounds the total.
Left as is, it would cause no problems with the IRS. Our program is tested by the IRS and has been approved. If you would like to see them be the same amount, you would need to modify one of your individual entries by a slight amount.