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	$194.45	7.800%	$209.6171	$209.62	$209.60	$209.60
Purchase #2	$77.66	13.152%	$87.8738	$87.87	$87.85	$87.90
Purchase #3	$6.34	12.167%	$7.1114	$7.11	$7.10	$7.10
Purchase #4	$78.43	13.304%	$88.8643	$88.86	$88.85	$88.90
Purchase #5	$42.51	8.454%	$46.1038	$46.10	$46.10	$46.10
Purchase #6	$190.64	3.311%	$196.9521	$196.95	$196.95	$197.00
Purchase #7	$46.40	9.734%	$50.9166	$50.92	$50.90	$50.90
7 purchase totals =	$636.43		$687.4391	$687.43	$687.35	$687.50