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	$56.29	10.331%	$62.1053	$62.11	$62.10	$62.10
Purchase #2	$42.32	8.821%	$46.053	$46.05	$46.05	$46.10
Purchase #3	$138.89	6.627%	$148.0942	$148.09	$148.10	$148.10
Purchase #4	$6.76	10.322%	$7.4578	$7.46	$7.45	$7.50
Purchase #5	$227.32	9.451%	$248.804	$248.80	$248.80	$248.80
Purchase #6	$27.72	12.871%	$31.2878	$31.29	$31.30	$31.30
Purchase #7	$152.65	12.415%	$171.6015	$171.60	$171.60	$171.60
7 purchase totals =	$651.95		$715.4036	$715.40	$715.40	$715.50