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	$139.70	8.593%	$151.7044	$151.70	$151.70	$151.70
Purchase #2	$210.84	5.386%	$222.1958	$222.20	$222.20	$222.20
Purchase #3	$182.44	13.432%	$206.9453	$206.95	$206.95	$206.90
Purchase #4	$6.85	7.816%	$7.3854	$7.39	$7.40	$7.40
Purchase #5	$29.87	13.631%	$33.9416	$33.94	$33.95	$33.90
Purchase #6	$49.31	6.611%	$52.5699	$52.57	$52.55	$52.60
Purchase #7	$100.46	11.129%	$111.6402	$111.64	$111.65	$111.60
7 purchase totals =	$719.47		$786.3826	$786.39	$786.40	$786.30