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	$180.70	7.665%	$194.5507	$194.55	$194.55	$194.60
Purchase #2	$142.96	5.591%	$150.9529	$150.95	$150.95	$151.00
Purchase #3	$38.91	6.372%	$41.3893	$41.39	$41.40	$41.40
Purchase #4	$44.73	13.411%	$50.7287	$50.73	$50.75	$50.70
Purchase #5	$48.70	5.339%	$51.3001	$51.30	$51.30	$51.30
Purchase #6	$77.48	6.484%	$82.5038	$82.50	$82.50	$82.50
Purchase #7	$146.81	9.580%	$160.8744	$160.87	$160.85	$160.90
7 purchase totals =	$680.29		$732.2999	$732.29	$732.30	$732.40