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	$179.48	7.273%	$192.5336	$192.53	$192.55	$192.50
Purchase #2	$115.71	5.647%	$122.2441	$122.24	$122.25	$122.20
Purchase #3	$40.82	7.203%	$43.7603	$43.76	$43.75	$43.80
Purchase #4	$183.96	4.287%	$191.8464	$191.85	$191.85	$191.80
Purchase #5	$27.52	10.791%	$30.4897	$30.49	$30.50	$30.50
Purchase #6	$55.57	7.788%	$59.8978	$59.90	$59.90	$59.90
Purchase #7	$197.42	5.592%	$208.4597	$208.46	$208.45	$208.50
7 purchase totals =	$800.48		$849.2316	$849.23	$849.25	$849.20