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	$175.39	10.187%	$193.257	$193.26	$193.25	$193.30
Purchase #2	$60.89	9.747%	$66.8249	$66.82	$66.80	$66.80
Purchase #3	$222.50	11.379%	$247.8183	$247.82	$247.80	$247.80
Purchase #4	$22.34	9.154%	$24.385	$24.39	$24.40	$24.40
Purchase #5	$241.51	12.803%	$272.4305	$272.43	$272.45	$272.40
Purchase #6	$233.96	3.258%	$241.5824	$241.58	$241.60	$241.60
Purchase #7	$62.83	3.106%	$64.7815	$64.78	$64.80	$64.80
7 purchase totals =	$1,019.42		$1,111.0796	$1,111.08	$1,111.10	$1,111.10