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	$182.87	9.650%	$200.517	$200.52	$200.50	$200.50
Purchase #2	$45.78	10.583%	$50.6249	$50.62	$50.60	$50.60
Purchase #3	$143.66	6.273%	$152.6718	$152.67	$152.65	$152.70
Purchase #4	$190.32	5.338%	$200.4793	$200.48	$200.50	$200.50
Purchase #5	$101.47	5.225%	$106.7718	$106.77	$106.75	$106.80
Purchase #6	$90.52	5.665%	$95.648	$95.65	$95.65	$95.60
Purchase #7	$186.71	9.451%	$204.356	$204.36	$204.35	$204.40
7 purchase totals =	$941.33		$1,011.0688	$1,011.07	$1,011.00	$1,011.10