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	$215.82	13.654%	$245.2881	$245.29	$245.30	$245.30
Purchase #2	$145.87	12.768%	$164.4947	$164.49	$164.50	$164.50
Purchase #3	$50.78	10.536%	$56.1302	$56.13	$56.15	$56.10
Purchase #4	$198.62	3.289%	$205.1526	$205.15	$205.15	$205.20
Purchase #5	$41.78	3.704%	$43.3275	$43.33	$43.35	$43.30
Purchase #6	$100.66	5.152%	$105.846	$105.85	$105.85	$105.80
Purchase #7	$190.51	6.129%	$202.1864	$202.19	$202.20	$202.20
7 purchase totals =	$944.04		$1,022.4255	$1,022.43	$1,022.50	$1,022.40