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	$191.73	7.206%	$205.5461	$205.55	$205.55	$205.50
Purchase #2	$98.72	6.700%	$105.3342	$105.33	$105.35	$105.30
Purchase #3	$98.25	13.615%	$111.6267	$111.63	$111.65	$111.60
Purchase #4	$247.66	6.256%	$263.1536	$263.15	$263.15	$263.20
Purchase #5	$69.58	5.523%	$73.4229	$73.42	$73.40	$73.40
Purchase #6	$173.50	10.143%	$191.0981	$191.10	$191.10	$191.10
Purchase #7	$190.78	5.229%	$200.7559	$200.76	$200.75	$200.80
7 purchase totals =	$1,070.22		$1,150.9375	$1,150.94	$1,150.95	$1,150.90