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	$105.60	5.450%	$111.3552	$111.36	$111.35	$111.40
Purchase #2	$179.31	6.254%	$190.524	$190.52	$190.50	$190.50
Purchase #3	$182.82	12.542%	$205.7493	$205.75	$205.75	$205.70
Purchase #4	$199.61	11.327%	$222.2198	$222.22	$222.20	$222.20
Purchase #5	$62.84	11.236%	$69.9007	$69.90	$69.90	$69.90
Purchase #6	$183.88	11.270%	$204.6033	$204.60	$204.60	$204.60
Purchase #7	$155.65	7.717%	$167.6615	$167.66	$167.65	$167.70
7 purchase totals =	$1,069.71		$1,172.0138	$1,172.01	$1,171.95	$1,172.00