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	$77.48	10.849%	$85.8858	$85.89	$85.90	$85.90
Purchase #2	$10.60	4.381%	$11.0644	$11.06	$11.05	$11.10
Purchase #3	$53.96	6.540%	$57.489	$57.49	$57.50	$57.50
Purchase #4	$59.51	10.506%	$65.7621	$65.76	$65.75	$65.80
Purchase #5	$195.46	11.205%	$217.3613	$217.36	$217.35	$217.40
Purchase #6	$236.46	4.598%	$247.3324	$247.33	$247.35	$247.30
Purchase #7	$184.71	8.702%	$200.7835	$200.78	$200.80	$200.80
7 purchase totals =	$818.18		$885.6785	$885.67	$885.70	$885.80