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	$229.86	7.242%	$246.5065	$246.51	$246.50	$246.50
Purchase #2	$147.54	6.114%	$156.5606	$156.56	$156.55	$156.60
Purchase #3	$25.34	3.335%	$26.1851	$26.19	$26.20	$26.20
Purchase #4	$226.86	8.507%	$246.159	$246.16	$246.15	$246.20
Purchase #5	$80.50	12.563%	$90.6132	$90.61	$90.60	$90.60
Purchase #6	$247.55	12.165%	$277.6645	$277.66	$277.65	$277.70
Purchase #7	$54.42	9.540%	$59.6117	$59.61	$59.60	$59.60
7 purchase totals =	$1,012.07		$1,103.3006	$1,103.30	$1,103.25	$1,103.40