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	$181.41	8.329%	$196.5196	$196.52	$196.50	$196.50
Purchase #2	$125.49	13.653%	$142.6231	$142.62	$142.60	$142.60
Purchase #3	$134.71	3.825%	$139.8627	$139.86	$139.85	$139.90
Purchase #4	$145.90	11.367%	$162.4845	$162.48	$162.50	$162.50
Purchase #5	$183.33	8.706%	$199.2907	$199.29	$199.30	$199.30
Purchase #6	$183.26	4.506%	$191.5177	$191.52	$191.50	$191.50
Purchase #7	$113.92	5.164%	$119.8028	$119.80	$119.80	$119.80
7 purchase totals =	$1,068.02		$1,152.1011	$1,152.09	$1,152.05	$1,152.10