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	$244.94	4.699%	$256.4497	$256.45	$256.45	$256.40
Purchase #2	$92.73	3.854%	$96.3038	$96.30	$96.30	$96.30
Purchase #3	$85.44	4.610%	$89.3788	$89.38	$89.40	$89.40
Purchase #4	$205.77	6.181%	$218.4886	$218.49	$218.50	$218.50
Purchase #5	$11.82	3.796%	$12.2687	$12.27	$12.25	$12.30
Purchase #6	$58.79	6.739%	$62.7519	$62.75	$62.75	$62.80
Purchase #7	$248.66	11.558%	$277.4001	$277.40	$277.40	$277.40
7 purchase totals =	$948.15		$1,013.0416	$1,013.04	$1,013.05	$1,013.10