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	$157.55	10.475%	$174.0534	$174.05	$174.05	$174.10
Purchase #2	$51.89	5.789%	$54.8939	$54.89	$54.90	$54.90
Purchase #3	$193.83	5.439%	$204.3724	$204.37	$204.35	$204.40
Purchase #4	$125.93	13.417%	$142.826	$142.83	$142.85	$142.80
Purchase #5	$125.77	9.451%	$137.6565	$137.66	$137.65	$137.70
Purchase #6	$153.62	11.831%	$171.7948	$171.79	$171.80	$171.80
Purchase #7	$200.28	12.648%	$225.6114	$225.61	$225.60	$225.60
7 purchase totals =	$1,008.87		$1,111.2084	$1,111.20	$1,111.20	$1,111.30