Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$196.63	11.288%	$218.8256	$218.83	$218.85	$218.80
Purchase #2	$176.72	4.168%	$184.0857	$184.09	$184.10	$184.10
Purchase #3	$81.33	11.377%	$90.5829	$90.58	$90.60	$90.60
Purchase #4	$11.88	11.675%	$13.267	$13.27	$13.25	$13.30
Purchase #5	$173.83	8.614%	$188.8037	$188.80	$188.80	$188.80
Purchase #6	$143.89	8.149%	$155.6156	$155.62	$155.60	$155.60
Purchase #7	$182.84	12.695%	$206.0515	$206.05	$206.05	$206.10
7 purchase totals =	$967.12		$1,057.2320	$1,057.24	$1,057.25	$1,057.30