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	$215.35	13.765%	$244.9929	$244.99	$245.00	$245.00
Purchase #2	$72.60	13.631%	$82.4961	$82.50	$82.50	$82.50
Purchase #3	$222.92	11.146%	$247.7667	$247.77	$247.75	$247.80
Purchase #4	$72.57	13.579%	$82.4243	$82.42	$82.40	$82.40
Purchase #5	$148.95	13.747%	$169.4262	$169.43	$169.45	$169.40
Purchase #6	$40.44	5.263%	$42.5684	$42.57	$42.55	$42.60
Purchase #7	$198.76	8.283%	$215.2233	$215.22	$215.20	$215.20
7 purchase totals =	$971.59		$1,084.8979	$1,084.90	$1,084.85	$1,084.90