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	$177.90	8.299%	$192.6639	$192.66	$192.65	$192.70
Purchase #2	$13.75	6.729%	$14.6752	$14.68	$14.70	$14.70
Purchase #3	$173.52	13.179%	$196.3882	$196.39	$196.40	$196.40
Purchase #4	$20.50	5.352%	$21.5972	$21.60	$21.60	$21.60
Purchase #5	$243.28	3.287%	$251.2766	$251.28	$251.30	$251.30
Purchase #6	$232.48	9.603%	$254.8051	$254.81	$254.80	$254.80
Purchase #7	$172.60	4.461%	$180.2997	$180.30	$180.30	$180.30
7 purchase totals =	$1,034.03		$1,111.7059	$1,111.72	$1,111.75	$1,111.80