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	$104.68	6.726%	$111.7208	$111.72	$111.70	$111.70
Purchase #2	$20.57	8.226%	$22.2621	$22.26	$22.25	$22.30
Purchase #3	$60.55	8.721%	$65.8306	$65.83	$65.85	$65.80
Purchase #4	$222.94	12.539%	$250.8944	$250.89	$250.90	$250.90
Purchase #5	$182.38	11.645%	$203.6182	$203.62	$203.60	$203.60
Purchase #6	$201.29	11.705%	$224.851	$224.85	$224.85	$224.90
Purchase #7	$241.38	8.725%	$262.4404	$262.44	$262.45	$262.40
7 purchase totals =	$1,033.79		$1,141.6175	$1,141.61	$1,141.60	$1,141.60