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	$207.84	7.212%	$222.8294	$222.83	$222.85	$222.80
Purchase #2	$226.49	7.127%	$242.6319	$242.63	$242.65	$242.60
Purchase #3	$247.29	3.656%	$256.3309	$256.33	$256.35	$256.30
Purchase #4	$161.89	12.439%	$182.0275	$182.03	$182.05	$182.00
Purchase #5	$194.78	13.805%	$221.6694	$221.67	$221.65	$221.70
Purchase #6	$188.72	11.179%	$209.817	$209.82	$209.80	$209.80
Purchase #7	$93.76	6.838%	$100.1713	$100.17	$100.15	$100.20
7 purchase totals =	$1,320.77		$1,435.4774	$1,435.48	$1,435.50	$1,435.40