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	$94.93	11.592%	$105.9343	$105.93	$105.95	$105.90
Purchase #2	$163.61	9.380%	$178.9566	$178.96	$178.95	$179.00
Purchase #3	$235.66	8.439%	$255.5473	$255.55	$255.55	$255.50
Purchase #4	$67.62	3.682%	$70.1098	$70.11	$70.10	$70.10
Purchase #5	$161.55	10.423%	$178.3884	$178.39	$178.40	$178.40
Purchase #6	$143.97	12.166%	$161.4854	$161.49	$161.50	$161.50
Purchase #7	$61.88	11.565%	$69.0364	$69.04	$69.05	$69.00
7 purchase totals =	$929.22		$1,019.4582	$1,019.47	$1,019.50	$1,019.40