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	$218.72	3.284%	$225.9028	$225.90	$225.90	$225.90
Purchase #2	$30.63	6.273%	$32.5514	$32.55	$32.55	$32.60
Purchase #3	$166.64	11.389%	$185.6186	$185.62	$185.60	$185.60
Purchase #4	$131.49	8.284%	$142.3826	$142.38	$142.40	$142.40
Purchase #5	$172.90	13.213%	$195.7453	$195.75	$195.75	$195.70
Purchase #6	$179.94	4.802%	$188.5807	$188.58	$188.60	$188.60
Purchase #7	$173.27	13.135%	$196.029	$196.03	$196.05	$196.00
7 purchase totals =	$1,073.59		$1,166.8104	$1,166.81	$1,166.85	$1,166.80