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	$104.55	7.790%	$112.6944	$112.69	$112.70	$112.70
Purchase #2	$241.67	7.392%	$259.5342	$259.53	$259.55	$259.50
Purchase #3	$65.32	3.446%	$67.5709	$67.57	$67.55	$67.60
Purchase #4	$72.70	7.169%	$77.9119	$77.91	$77.90	$77.90
Purchase #5	$106.26	10.697%	$117.6266	$117.63	$117.65	$117.60
Purchase #6	$245.39	6.866%	$262.2385	$262.24	$262.25	$262.20
Purchase #7	$226.89	12.217%	$254.6092	$254.61	$254.60	$254.60
7 purchase totals =	$1,062.78		$1,152.1857	$1,152.18	$1,152.20	$1,152.10