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	$43.61	11.460%	$48.6077	$48.61	$48.60	$48.60
Purchase #2	$220.65	6.296%	$234.5421	$234.54	$234.55	$234.50
Purchase #3	$185.62	10.849%	$205.7579	$205.76	$205.75	$205.80
Purchase #4	$218.63	11.273%	$243.2762	$243.28	$243.30	$243.30
Purchase #5	$89.94	8.841%	$97.8916	$97.89	$97.90	$97.90
Purchase #6	$90.52	11.756%	$101.1615	$101.16	$101.15	$101.20
Purchase #7	$108.62	5.786%	$114.9048	$114.90	$114.90	$114.90
7 purchase totals =	$957.59		$1,046.1418	$1,046.14	$1,046.15	$1,046.20