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	$213.40	7.727%	$229.8894	$229.89	$229.90	$229.90
Purchase #2	$73.47	6.267%	$78.0744	$78.07	$78.05	$78.10
Purchase #3	$170.58	8.342%	$184.8098	$184.81	$184.80	$184.80
Purchase #4	$163.87	7.129%	$175.5523	$175.55	$175.55	$175.60
Purchase #5	$38.42	12.158%	$43.0911	$43.09	$43.10	$43.10
Purchase #6	$191.94	9.835%	$210.8173	$210.82	$210.80	$210.80
Purchase #7	$86.34	3.256%	$89.1512	$89.15	$89.15	$89.20
7 purchase totals =	$938.02		$1,011.3855	$1,011.38	$1,011.35	$1,011.50