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	$59.52	3.266%	$61.4639	$61.46	$61.45	$61.50
Purchase #2	$138.47	3.338%	$143.0921	$143.09	$143.10	$143.10
Purchase #3	$200.78	9.247%	$219.3461	$219.35	$219.35	$219.30
Purchase #4	$99.92	4.198%	$104.1146	$104.11	$104.10	$104.10
Purchase #5	$186.89	6.715%	$199.4397	$199.44	$199.45	$199.40
Purchase #6	$90.82	3.270%	$93.7898	$93.79	$93.80	$93.80
Purchase #7	$226.75	5.764%	$239.8199	$239.82	$239.80	$239.80
7 purchase totals =	$1,003.15		$1,061.0661	$1,061.06	$1,061.05	$1,061.00