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	$118.57	5.517%	$125.1115	$125.11	$125.10	$125.10
Purchase #2	$78.38	13.667%	$89.0922	$89.09	$89.10	$89.10
Purchase #3	$81.51	10.296%	$89.9023	$89.90	$89.90	$89.90
Purchase #4	$215.85	8.478%	$234.1498	$234.15	$234.15	$234.10
Purchase #5	$214.94	12.165%	$241.0875	$241.09	$241.10	$241.10
Purchase #6	$110.93	4.113%	$115.4926	$115.49	$115.50	$115.50
Purchase #7	$189.49	5.363%	$199.6523	$199.65	$199.65	$199.70
7 purchase totals =	$1,009.67		$1,094.4882	$1,094.48	$1,094.50	$1,094.50