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	$195.71	8.647%	$212.633	$212.63	$212.65	$212.60
Purchase #2	$142.43	12.864%	$160.7522	$160.75	$160.75	$160.80
Purchase #3	$74.77	11.836%	$83.6198	$83.62	$83.60	$83.60
Purchase #4	$61.77	3.453%	$63.9029	$63.90	$63.90	$63.90
Purchase #5	$101.73	9.113%	$111.0007	$111.00	$111.00	$111.00
Purchase #6	$233.83	11.258%	$260.1546	$260.15	$260.15	$260.20
Purchase #7	$144.59	12.239%	$162.2864	$162.29	$162.30	$162.30
7 purchase totals =	$954.83		$1,054.3496	$1,054.34	$1,054.35	$1,054.40