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	$187.67	3.656%	$194.5312	$194.53	$194.55	$194.50
Purchase #2	$146.78	3.570%	$152.02	$152.02	$152.00	$152.00
Purchase #3	$114.84	11.860%	$128.46	$128.46	$128.45	$128.50
Purchase #4	$95.71	5.366%	$100.8458	$100.85	$100.85	$100.80
Purchase #5	$248.78	12.198%	$279.1262	$279.13	$279.15	$279.10
Purchase #6	$157.85	10.517%	$174.4511	$174.45	$174.45	$174.50
Purchase #7	$58.55	13.850%	$66.6592	$66.66	$66.65	$66.70
7 purchase totals =	$1,010.18		$1,096.0935	$1,096.10	$1,096.10	$1,096.10