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	$147.68	5.551%	$155.8777	$155.88	$155.90	$155.90
Purchase #2	$112.67	5.517%	$118.886	$118.89	$118.90	$118.90
Purchase #3	$167.55	4.627%	$175.3025	$175.30	$175.30	$175.30
Purchase #4	$58.83	10.273%	$64.8736	$64.87	$64.85	$64.90
Purchase #5	$39.53	6.640%	$42.1548	$42.15	$42.15	$42.20
Purchase #6	$206.83	11.864%	$231.3683	$231.37	$231.35	$231.40
Purchase #7	$160.42	8.734%	$174.4311	$174.43	$174.45	$174.40
7 purchase totals =	$893.51		$962.8940	$962.89	$962.90	$963.00