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	$150.77	5.302%	$158.7638	$158.76	$158.75	$158.80
Purchase #2	$161.55	6.827%	$172.579	$172.58	$172.60	$172.60
Purchase #3	$103.71	13.128%	$117.325	$117.33	$117.35	$117.30
Purchase #4	$133.37	10.429%	$147.2792	$147.28	$147.30	$147.30
Purchase #5	$165.27	10.509%	$182.6382	$182.64	$182.65	$182.60
Purchase #6	$41.50	8.489%	$45.0229	$45.02	$45.00	$45.00
Purchase #7	$176.48	10.505%	$195.0192	$195.02	$195.00	$195.00
7 purchase totals =	$932.65		$1,018.6273	$1,018.63	$1,018.65	$1,018.60