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	$105.47	7.231%	$113.0965	$113.10	$113.10	$113.10
Purchase #2	$107.33	5.307%	$113.026	$113.03	$113.05	$113.00
Purchase #3	$102.34	9.146%	$111.7	$111.70	$111.70	$111.70
Purchase #4	$10.80	5.250%	$11.367	$11.37	$11.35	$11.40
Purchase #5	$120.54	6.593%	$128.4872	$128.49	$128.50	$128.50
Purchase #6	$188.81	5.533%	$199.2569	$199.26	$199.25	$199.30
Purchase #7	$80.52	11.697%	$89.9384	$89.94	$89.95	$89.90
7 purchase totals =	$715.81		$766.8720	$766.89	$766.90	$766.90