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	$174.95	11.746%	$195.4996	$195.50	$195.50	$195.50
Purchase #2	$8.31	10.233%	$9.1604	$9.16	$9.15	$9.20
Purchase #3	$133.77	9.696%	$146.7403	$146.74	$146.75	$146.70
Purchase #4	$210.90	12.142%	$236.5075	$236.51	$236.50	$236.50
Purchase #5	$162.31	5.618%	$171.4286	$171.43	$171.45	$171.40
Purchase #6	$224.42	9.420%	$245.5604	$245.56	$245.55	$245.60
Purchase #7	$52.86	13.278%	$59.8788	$59.88	$59.90	$59.90
7 purchase totals =	$967.52		$1,064.7756	$1,064.78	$1,064.80	$1,064.80