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	$178.59	8.271%	$193.3612	$193.36	$193.35	$193.40
Purchase #2	$100.72	5.145%	$105.902	$105.90	$105.90	$105.90
Purchase #3	$210.99	9.276%	$230.5614	$230.56	$230.55	$230.60
Purchase #4	$40.90	10.713%	$45.2816	$45.28	$45.30	$45.30
Purchase #5	$152.50	6.165%	$161.9016	$161.90	$161.90	$161.90
Purchase #6	$177.85	3.713%	$184.4536	$184.45	$184.45	$184.50
Purchase #7	$85.91	11.391%	$95.696	$95.70	$95.70	$95.70
7 purchase totals =	$947.46		$1,017.1574	$1,017.15	$1,017.15	$1,017.30