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	$60.61	4.196%	$63.1532	$63.15	$63.15	$63.20
Purchase #2	$46.88	13.798%	$53.3485	$53.35	$53.35	$53.30
Purchase #3	$75.76	12.687%	$85.3717	$85.37	$85.35	$85.40
Purchase #4	$50.85	5.805%	$53.8018	$53.80	$53.80	$53.80
Purchase #5	$55.31	13.349%	$62.6933	$62.69	$62.70	$62.70
Purchase #6	$211.46	6.451%	$225.1013	$225.10	$225.10	$225.10
Purchase #7	$179.48	4.514%	$187.5817	$187.58	$187.60	$187.60
7 purchase totals =	$680.35		$731.0515	$731.04	$731.05	$731.10