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	$196.54	7.723%	$211.7188	$211.72	$211.70	$211.70
Purchase #2	$92.67	7.828%	$99.9242	$99.92	$99.90	$99.90
Purchase #3	$59.75	8.677%	$64.9345	$64.93	$64.95	$64.90
Purchase #4	$204.47	13.869%	$232.8279	$232.83	$232.85	$232.80
Purchase #5	$233.37	5.210%	$245.5286	$245.53	$245.55	$245.50
Purchase #6	$77.86	12.430%	$87.538	$87.54	$87.55	$87.50
Purchase #7	$137.78	5.705%	$145.6403	$145.64	$145.65	$145.60
7 purchase totals =	$1,002.44		$1,088.1123	$1,088.11	$1,088.15	$1,087.90