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	$222.39	10.163%	$244.9915	$244.99	$245.00	$245.00
Purchase #2	$128.59	12.572%	$144.7563	$144.76	$144.75	$144.80
Purchase #3	$114.92	7.766%	$123.8447	$123.84	$123.85	$123.80
Purchase #4	$6.67	6.855%	$7.1272	$7.13	$7.15	$7.10
Purchase #5	$227.78	7.617%	$245.13	$245.13	$245.15	$245.10
Purchase #6	$238.43	10.150%	$262.6306	$262.63	$262.65	$262.60
Purchase #7	$137.62	4.302%	$143.5404	$143.54	$143.55	$143.50
7 purchase totals =	$1,076.40		$1,172.0207	$1,172.02	$1,172.10	$1,171.90