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	$180.52	8.416%	$195.7126	$195.71	$195.70	$195.70
Purchase #2	$85.33	10.676%	$94.4398	$94.44	$94.45	$94.40
Purchase #3	$49.99	11.748%	$55.8628	$55.86	$55.85	$55.90
Purchase #4	$55.27	8.466%	$59.9492	$59.95	$59.95	$59.90
Purchase #5	$142.92	6.405%	$152.074	$152.07	$152.05	$152.10
Purchase #6	$119.66	9.706%	$131.2742	$131.27	$131.25	$131.30
Purchase #7	$23.84	4.507%	$24.9145	$24.91	$24.90	$24.90
7 purchase totals =	$657.53		$714.2271	$714.21	$714.15	$714.20