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	$159.51	11.621%	$178.0467	$178.05	$178.05	$178.00
Purchase #2	$172.76	5.187%	$181.7211	$181.72	$181.70	$181.70
Purchase #3	$140.51	5.378%	$148.0666	$148.07	$148.05	$148.10
Purchase #4	$114.93	11.393%	$128.024	$128.02	$128.00	$128.00
Purchase #5	$16.82	11.631%	$18.7763	$18.78	$18.80	$18.80
Purchase #6	$190.53	13.144%	$215.5733	$215.57	$215.55	$215.60
Purchase #7	$143.98	7.736%	$155.1183	$155.12	$155.10	$155.10
7 purchase totals =	$939.04		$1,025.3263	$1,025.33	$1,025.25	$1,025.30