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	$174.51	9.657%	$191.3624	$191.36	$191.35	$191.40
Purchase #2	$92.67	8.729%	$100.7592	$100.76	$100.75	$100.80
Purchase #3	$154.65	5.182%	$162.664	$162.66	$162.65	$162.70
Purchase #4	$164.26	13.612%	$186.6191	$186.62	$186.60	$186.60
Purchase #5	$228.62	12.802%	$257.8879	$257.89	$257.90	$257.90
Purchase #6	$83.33	13.361%	$94.4637	$94.46	$94.45	$94.50
Purchase #7	$144.75	4.352%	$151.0495	$151.05	$151.05	$151.00
7 purchase totals =	$1,042.79		$1,144.8058	$1,144.80	$1,144.75	$1,144.90