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	$218.93	4.754%	$229.3379	$229.34	$229.35	$229.30
Purchase #2	$18.74	9.763%	$20.5696	$20.57	$20.55	$20.60
Purchase #3	$120.65	5.138%	$126.849	$126.85	$126.85	$126.80
Purchase #4	$56.45	5.104%	$59.3312	$59.33	$59.35	$59.30
Purchase #5	$208.69	3.452%	$215.894	$215.89	$215.90	$215.90
Purchase #6	$174.32	4.607%	$182.3509	$182.35	$182.35	$182.40
Purchase #7	$158.62	6.198%	$168.4513	$168.45	$168.45	$168.50
7 purchase totals =	$956.40		$1,002.7839	$1,002.78	$1,002.80	$1,002.80