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	$49.26	9.342%	$53.8619	$53.86	$53.85	$53.90
Purchase #2	$145.33	4.589%	$151.9992	$152.00	$152.00	$152.00
Purchase #3	$91.45	10.866%	$101.387	$101.39	$101.40	$101.40
Purchase #4	$250.60	8.351%	$271.5276	$271.53	$271.55	$271.50
Purchase #5	$89.96	5.616%	$95.0122	$95.01	$95.00	$95.00
Purchase #6	$206.65	13.667%	$234.8929	$234.89	$234.90	$234.90
Purchase #7	$96.80	11.281%	$107.72	$107.72	$107.70	$107.70
7 purchase totals =	$930.05		$1,016.4008	$1,016.40	$1,016.40	$1,016.40