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	$131.66	10.413%	$145.3698	$145.37	$145.35	$145.40
Purchase #2	$65.47	12.222%	$73.4717	$73.47	$73.45	$73.50
Purchase #3	$142.57	7.742%	$153.6078	$153.61	$153.60	$153.60
Purchase #4	$116.49	9.659%	$127.7418	$127.74	$127.75	$127.70
Purchase #5	$206.98	7.843%	$223.2134	$223.21	$223.20	$223.20
Purchase #6	$186.74	3.682%	$193.6158	$193.62	$193.60	$193.60
Purchase #7	$91.70	8.692%	$99.6706	$99.67	$99.65	$99.70
7 purchase totals =	$941.61		$1,016.6909	$1,016.69	$1,016.60	$1,016.70