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	$137.43	8.398%	$148.9714	$148.97	$148.95	$149.00
Purchase #2	$37.48	8.643%	$40.7194	$40.72	$40.70	$40.70
Purchase #3	$186.64	11.644%	$208.3724	$208.37	$208.35	$208.40
Purchase #4	$207.64	10.429%	$229.2948	$229.29	$229.30	$229.30
Purchase #5	$176.33	7.817%	$190.1137	$190.11	$190.10	$190.10
Purchase #6	$204.52	10.204%	$225.3892	$225.39	$225.40	$225.40
Purchase #7	$72.50	11.855%	$81.0949	$81.09	$81.10	$81.10
7 purchase totals =	$1,022.54		$1,123.9558	$1,123.94	$1,123.90	$1,124.00