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	$94.38	9.206%	$103.0686	$103.07	$103.05	$103.10
Purchase #2	$199.46	12.516%	$224.4244	$224.42	$224.40	$224.40
Purchase #3	$148.76	5.446%	$156.8615	$156.86	$156.85	$156.90
Purchase #4	$39.63	3.245%	$40.916	$40.92	$40.90	$40.90
Purchase #5	$194.56	3.153%	$200.6945	$200.69	$200.70	$200.70
Purchase #6	$167.87	10.660%	$185.7649	$185.76	$185.75	$185.80
Purchase #7	$108.80	7.155%	$116.5846	$116.58	$116.60	$116.60
7 purchase totals =	$953.46		$1,028.3145	$1,028.30	$1,028.25	$1,028.40