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	$163.31	3.280%	$168.6666	$168.67	$168.65	$168.70
Purchase #2	$213.47	4.719%	$223.5436	$223.54	$223.55	$223.50
Purchase #3	$134.67	10.300%	$148.541	$148.54	$148.55	$148.50
Purchase #4	$199.43	5.714%	$210.8254	$210.83	$210.85	$210.80
Purchase #5	$52.91	11.123%	$58.7952	$58.80	$58.80	$58.80
Purchase #6	$63.32	7.772%	$68.2412	$68.24	$68.25	$68.20
Purchase #7	$172.71	6.436%	$183.8256	$183.83	$183.85	$183.80
7 purchase totals =	$999.82		$1,062.4386	$1,062.45	$1,062.50	$1,062.30