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	$201.83	6.463%	$214.8743	$214.87	$214.85	$214.90
Purchase #2	$74.95	11.103%	$83.2717	$83.27	$83.25	$83.30
Purchase #3	$59.41	3.487%	$61.4816	$61.48	$61.50	$61.50
Purchase #4	$218.73	8.465%	$237.2455	$237.25	$237.25	$237.20
Purchase #5	$76.84	7.590%	$82.6722	$82.67	$82.65	$82.70
Purchase #6	$141.92	12.361%	$159.4627	$159.46	$159.45	$159.50
Purchase #7	$240.37	13.538%	$272.9113	$272.91	$272.90	$272.90
7 purchase totals =	$1,014.05		$1,111.9193	$1,111.91	$1,111.85	$1,112.00