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	$195.36	13.561%	$221.8528	$221.85	$221.85	$221.90
Purchase #2	$186.54	11.616%	$208.2085	$208.21	$208.20	$208.20
Purchase #3	$161.43	6.246%	$171.5129	$171.51	$171.50	$171.50
Purchase #4	$22.76	9.574%	$24.939	$24.94	$24.95	$24.90
Purchase #5	$106.27	4.843%	$111.4167	$111.42	$111.40	$111.40
Purchase #6	$132.96	13.743%	$151.2327	$151.23	$151.25	$151.20
Purchase #7	$175.56	11.852%	$196.3674	$196.37	$196.35	$196.40
7 purchase totals =	$980.88		$1,085.5300	$1,085.53	$1,085.50	$1,085.50