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	$195.72	9.174%	$213.6754	$213.68	$213.70	$213.70
Purchase #2	$239.55	13.351%	$271.5323	$271.53	$271.55	$271.50
Purchase #3	$36.53	6.823%	$39.0224	$39.02	$39.00	$39.00
Purchase #4	$46.39	4.504%	$48.4794	$48.48	$48.50	$48.50
Purchase #5	$108.62	13.325%	$123.0936	$123.09	$123.10	$123.10
Purchase #6	$48.69	7.799%	$52.4873	$52.49	$52.50	$52.50
Purchase #7	$236.77	9.645%	$259.6065	$259.61	$259.60	$259.60
7 purchase totals =	$912.27		$1,007.8969	$1,007.90	$1,007.95	$1,007.90