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	$106.87	4.110%	$111.2624	$111.26	$111.25	$111.30
Purchase #2	$145.29	4.117%	$151.2716	$151.27	$151.25	$151.30
Purchase #3	$159.34	5.499%	$168.1021	$168.10	$168.10	$168.10
Purchase #4	$242.66	3.321%	$250.7187	$250.72	$250.70	$250.70
Purchase #5	$103.47	5.175%	$108.8246	$108.82	$108.80	$108.80
Purchase #6	$250.49	3.656%	$259.6479	$259.65	$259.65	$259.60
Purchase #7	$73.43	12.551%	$82.6462	$82.65	$82.65	$82.60
7 purchase totals =	$1,081.55		$1,132.4735	$1,132.47	$1,132.40	$1,132.40