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	$146.84	10.671%	$162.5093	$162.51	$162.50	$162.50
Purchase #2	$213.53	7.408%	$229.3483	$229.35	$229.35	$229.30
Purchase #3	$104.37	6.847%	$111.5162	$111.52	$111.50	$111.50
Purchase #4	$107.73	9.587%	$118.0581	$118.06	$118.05	$118.10
Purchase #5	$223.78	7.347%	$240.2211	$240.22	$240.20	$240.20
Purchase #6	$233.61	7.719%	$251.6424	$251.64	$251.65	$251.60
Purchase #7	$44.57	10.577%	$49.2842	$49.28	$49.30	$49.30
7 purchase totals =	$1,074.43		$1,162.5796	$1,162.58	$1,162.55	$1,162.50