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	$13.39	4.114%	$13.9409	$13.94	$13.95	$13.90
Purchase #2	$106.93	10.370%	$118.0186	$118.02	$118.00	$118.00
Purchase #3	$199.45	11.650%	$222.6859	$222.69	$222.70	$222.70
Purchase #4	$224.99	13.722%	$255.8631	$255.86	$255.85	$255.90
Purchase #5	$150.38	5.282%	$158.3231	$158.32	$158.30	$158.30
Purchase #6	$83.39	3.470%	$86.2836	$86.28	$86.30	$86.30
Purchase #7	$159.86	4.518%	$167.0825	$167.08	$167.10	$167.10
7 purchase totals =	$938.39		$1,022.1977	$1,022.19	$1,022.20	$1,022.20