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	$149.77	7.455%	$160.9354	$160.94	$160.95	$160.90
Purchase #2	$225.35	8.558%	$244.6355	$244.64	$244.65	$244.60
Purchase #3	$208.98	5.816%	$221.1343	$221.13	$221.15	$221.10
Purchase #4	$65.47	10.495%	$72.3411	$72.34	$72.35	$72.30
Purchase #5	$84.57	12.363%	$95.0254	$95.03	$95.05	$95.00
Purchase #6	$213.51	7.297%	$229.0898	$229.09	$229.10	$229.10
Purchase #7	$63.96	12.364%	$71.868	$71.87	$71.85	$71.90
7 purchase totals =	$1,011.61		$1,095.0295	$1,095.04	$1,095.10	$1,094.90