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	$190.44	12.816%	$214.8468	$214.85	$214.85	$214.80
Purchase #2	$50.89	8.369%	$55.149	$55.15	$55.15	$55.10
Purchase #3	$59.94	11.281%	$66.7018	$66.70	$66.70	$66.70
Purchase #4	$250.97	9.267%	$274.2274	$274.23	$274.25	$274.20
Purchase #5	$73.59	6.542%	$78.4043	$78.40	$78.40	$78.40
Purchase #6	$200.87	10.737%	$222.4374	$222.44	$222.45	$222.40
Purchase #7	$171.92	12.393%	$193.226	$193.23	$193.25	$193.20
7 purchase totals =	$998.62		$1,104.9927	$1,105.00	$1,105.05	$1,104.80