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	$61.91	10.348%	$68.3164	$68.32	$68.30	$68.30
Purchase #2	$111.78	13.374%	$126.7295	$126.73	$126.75	$126.70
Purchase #3	$95.67	4.748%	$100.2124	$100.21	$100.20	$100.20
Purchase #4	$168.58	10.349%	$186.0263	$186.03	$186.05	$186.00
Purchase #5	$204.62	5.835%	$216.5596	$216.56	$216.55	$216.60
Purchase #6	$162.36	5.667%	$171.5609	$171.56	$171.55	$171.60
Purchase #7	$189.43	4.601%	$198.1457	$198.15	$198.15	$198.10
7 purchase totals =	$994.35		$1,067.5508	$1,067.56	$1,067.55	$1,067.50