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	$73.49	3.346%	$75.949	$75.95	$75.95	$75.90
Purchase #2	$179.56	6.864%	$191.885	$191.89	$191.90	$191.90
Purchase #3	$148.63	11.480%	$165.6927	$165.69	$165.70	$165.70
Purchase #4	$231.55	10.310%	$255.4228	$255.42	$255.40	$255.40
Purchase #5	$176.26	8.478%	$191.2033	$191.20	$191.20	$191.20
Purchase #6	$167.80	8.616%	$182.2576	$182.26	$182.25	$182.30
Purchase #7	$17.49	6.308%	$18.5933	$18.59	$18.60	$18.60
7 purchase totals =	$994.78		$1,081.0037	$1,081.00	$1,081.00	$1,081.00