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	$160.28	4.649%	$167.7314	$167.73	$167.75	$167.70
Purchase #2	$10.37	7.329%	$11.13	$11.13	$11.15	$11.10
Purchase #3	$19.36	10.340%	$21.3618	$21.36	$21.35	$21.40
Purchase #4	$136.98	11.347%	$152.5231	$152.52	$152.50	$152.50
Purchase #5	$56.69	6.742%	$60.512	$60.51	$60.50	$60.50
Purchase #6	$229.45	11.743%	$256.3943	$256.39	$256.40	$256.40
Purchase #7	$86.67	9.511%	$94.9132	$94.91	$94.90	$94.90
7 purchase totals =	$699.80		$764.5658	$764.55	$764.55	$764.50