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	$209.76	10.571%	$231.9337	$231.93	$231.95	$231.90
Purchase #2	$241.30	4.248%	$251.5504	$251.55	$251.55	$251.60
Purchase #3	$122.40	4.505%	$127.9141	$127.91	$127.90	$127.90
Purchase #4	$47.90	10.503%	$52.9309	$52.93	$52.95	$52.90
Purchase #5	$144.25	4.301%	$150.4542	$150.45	$150.45	$150.50
Purchase #6	$7.45	13.415%	$8.4494	$8.45	$8.45	$8.40
Purchase #7	$229.60	3.702%	$238.0998	$238.10	$238.10	$238.10
7 purchase totals =	$1,002.66		$1,061.3325	$1,061.32	$1,061.35	$1,061.30