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	$109.75	4.456%	$114.6405	$114.64	$114.65	$114.60
Purchase #2	$126.82	10.863%	$140.5965	$140.60	$140.60	$140.60
Purchase #3	$93.67	7.151%	$100.3683	$100.37	$100.35	$100.40
Purchase #4	$140.91	3.392%	$145.6897	$145.69	$145.70	$145.70
Purchase #5	$243.47	10.366%	$268.7081	$268.71	$268.70	$268.70
Purchase #6	$191.69	7.834%	$206.707	$206.71	$206.70	$206.70
Purchase #7	$183.85	6.745%	$196.2507	$196.25	$196.25	$196.30
7 purchase totals =	$1,090.16		$1,172.9608	$1,172.97	$1,172.95	$1,173.00