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	$87.80	8.548%	$95.3051	$95.31	$95.30	$95.30
Purchase #2	$66.54	8.449%	$72.162	$72.16	$72.15	$72.20
Purchase #3	$155.83	10.283%	$171.854	$171.85	$171.85	$171.90
Purchase #4	$243.49	10.553%	$269.1855	$269.19	$269.20	$269.20
Purchase #5	$52.56	3.448%	$54.3723	$54.37	$54.35	$54.40
Purchase #6	$81.29	10.205%	$89.5856	$89.59	$89.60	$89.60
Purchase #7	$239.76	5.728%	$253.4935	$253.49	$253.50	$253.50
7 purchase totals =	$927.27		$1,005.9580	$1,005.96	$1,005.95	$1,006.10