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	$141.38	10.730%	$156.5501	$156.55	$156.55	$156.60
Purchase #2	$93.56	7.158%	$100.257	$100.26	$100.25	$100.30
Purchase #3	$145.94	3.488%	$151.0304	$151.03	$151.05	$151.00
Purchase #4	$135.89	3.611%	$140.797	$140.80	$140.80	$140.80
Purchase #5	$69.53	3.351%	$71.86	$71.86	$71.85	$71.90
Purchase #6	$65.40	4.136%	$68.1049	$68.10	$68.10	$68.10
Purchase #7	$30.65	12.809%	$34.576	$34.58	$34.60	$34.60
7 purchase totals =	$682.35		$723.1754	$723.18	$723.20	$723.30