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	$196.66	7.669%	$211.7419	$211.74	$211.75	$211.70
Purchase #2	$178.87	9.404%	$195.6909	$195.69	$195.70	$195.70
Purchase #3	$247.68	8.853%	$269.6071	$269.61	$269.60	$269.60
Purchase #4	$90.86	10.558%	$100.453	$100.45	$100.45	$100.50
Purchase #5	$13.29	10.534%	$14.69	$14.69	$14.70	$14.70
Purchase #6	$65.39	11.787%	$73.0975	$73.10	$73.10	$73.10
Purchase #7	$118.35	7.505%	$127.2322	$127.23	$127.25	$127.20
7 purchase totals =	$911.10		$992.5126	$992.51	$992.55	$992.50