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	$108.42	8.561%	$117.7018	$117.70	$117.70	$117.70
Purchase #2	$82.46	3.316%	$85.1944	$85.19	$85.20	$85.20
Purchase #3	$162.25	6.307%	$172.4831	$172.48	$172.50	$172.50
Purchase #4	$108.98	3.296%	$112.572	$112.57	$112.55	$112.60
Purchase #5	$114.46	3.430%	$118.386	$118.39	$118.40	$118.40
Purchase #6	$244.66	5.671%	$258.5347	$258.53	$258.55	$258.50
Purchase #7	$151.71	13.863%	$172.7416	$172.74	$172.75	$172.70
7 purchase totals =	$972.94		$1,037.6136	$1,037.60	$1,037.65	$1,037.60