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	$229.89	7.641%	$247.4559	$247.46	$247.45	$247.50
Purchase #2	$76.40	8.104%	$82.5915	$82.59	$82.60	$82.60
Purchase #3	$246.28	5.660%	$260.2194	$260.22	$260.20	$260.20
Purchase #4	$45.42	8.502%	$49.2816	$49.28	$49.30	$49.30
Purchase #5	$78.60	7.467%	$84.4691	$84.47	$84.45	$84.50
Purchase #6	$57.30	7.303%	$61.4846	$61.48	$61.50	$61.50
Purchase #7	$217.89	3.315%	$225.1131	$225.11	$225.10	$225.10
7 purchase totals =	$951.78		$1,010.6152	$1,010.61	$1,010.60	$1,010.70