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	$176.70	11.348%	$196.7519	$196.75	$196.75	$196.80
Purchase #2	$35.44	4.136%	$36.9058	$36.91	$36.90	$36.90
Purchase #3	$94.95	5.229%	$99.9149	$99.91	$99.90	$99.90
Purchase #4	$87.64	3.244%	$90.483	$90.48	$90.50	$90.50
Purchase #5	$246.50	11.642%	$275.1975	$275.20	$275.20	$275.20
Purchase #6	$170.69	11.726%	$190.7051	$190.71	$190.70	$190.70
Purchase #7	$250.82	9.475%	$274.5852	$274.59	$274.60	$274.60
7 purchase totals =	$1,062.74		$1,164.5434	$1,164.55	$1,164.55	$1,164.60