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	$101.46	10.331%	$111.9418	$111.94	$111.95	$111.90
Purchase #2	$188.99	11.652%	$211.0111	$211.01	$211.00	$211.00
Purchase #3	$155.44	10.619%	$171.9462	$171.95	$171.95	$171.90
Purchase #4	$122.91	13.280%	$139.2324	$139.23	$139.25	$139.20
Purchase #5	$49.79	4.293%	$51.9275	$51.93	$51.95	$51.90
Purchase #6	$227.54	7.852%	$245.4064	$245.41	$245.40	$245.40
Purchase #7	$101.72	12.682%	$114.6201	$114.62	$114.60	$114.60
7 purchase totals =	$947.85		$1,046.0855	$1,046.09	$1,046.10	$1,045.90