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	$163.48	10.454%	$180.5702	$180.57	$180.55	$180.60
Purchase #2	$148.83	11.222%	$165.5317	$165.53	$165.55	$165.50
Purchase #3	$154.29	11.372%	$171.8359	$171.84	$171.85	$171.80
Purchase #4	$150.56	5.397%	$158.6857	$158.69	$158.70	$158.70
Purchase #5	$31.88	9.422%	$34.8837	$34.88	$34.90	$34.90
Purchase #6	$154.82	7.448%	$166.351	$166.35	$166.35	$166.40
Purchase #7	$145.65	8.581%	$158.1482	$158.15	$158.15	$158.10
7 purchase totals =	$949.51		$1,036.0064	$1,036.01	$1,036.05	$1,036.00