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	$176.89	3.710%	$183.4526	$183.45	$183.45	$183.50
Purchase #2	$185.82	9.848%	$204.1196	$204.12	$204.10	$204.10
Purchase #3	$45.46	5.728%	$48.0639	$48.06	$48.05	$48.10
Purchase #4	$80.48	3.796%	$83.535	$83.54	$83.55	$83.50
Purchase #5	$98.65	11.157%	$109.6564	$109.66	$109.65	$109.70
Purchase #6	$210.82	9.210%	$230.2365	$230.24	$230.25	$230.20
Purchase #7	$193.47	3.504%	$200.2492	$200.25	$200.25	$200.20
7 purchase totals =	$991.59		$1,059.3132	$1,059.32	$1,059.30	$1,059.30