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	$152.50	13.209%	$172.6437	$172.64	$172.65	$172.60
Purchase #2	$198.83	10.257%	$219.224	$219.22	$219.20	$219.20
Purchase #3	$27.69	4.127%	$28.8328	$28.83	$28.85	$28.80
Purchase #4	$133.86	13.596%	$152.0596	$152.06	$152.05	$152.10
Purchase #5	$189.61	5.817%	$200.6396	$200.64	$200.65	$200.60
Purchase #6	$37.33	5.644%	$39.4369	$39.44	$39.45	$39.40
Purchase #7	$232.99	6.370%	$247.8315	$247.83	$247.85	$247.80
7 purchase totals =	$972.81		$1,060.6681	$1,060.66	$1,060.70	$1,060.50