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	$233.82	12.415%	$262.8488	$262.85	$262.85	$262.80
Purchase #2	$205.82	4.224%	$214.5138	$214.51	$214.50	$214.50
Purchase #3	$212.92	11.224%	$236.8181	$236.82	$236.80	$236.80
Purchase #4	$226.38	7.486%	$243.3268	$243.33	$243.35	$243.30
Purchase #5	$87.86	13.364%	$99.6016	$99.60	$99.60	$99.60
Purchase #6	$57.25	5.617%	$60.4657	$60.47	$60.45	$60.50
Purchase #7	$32.61	13.750%	$37.0939	$37.09	$37.10	$37.10
7 purchase totals =	$1,056.66		$1,154.6687	$1,154.67	$1,154.65	$1,154.60