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	$169.45	12.471%	$190.5821	$190.58	$190.60	$190.60
Purchase #2	$184.93	5.240%	$194.6203	$194.62	$194.60	$194.60
Purchase #3	$82.83	3.228%	$85.5038	$85.50	$85.50	$85.50
Purchase #4	$124.27	4.800%	$130.235	$130.24	$130.25	$130.20
Purchase #5	$15.52	12.301%	$17.4291	$17.43	$17.45	$17.40
Purchase #6	$249.52	9.598%	$273.4689	$273.47	$273.45	$273.50
Purchase #7	$195.82	3.703%	$203.0712	$203.07	$203.05	$203.10
7 purchase totals =	$1,022.34		$1,094.9104	$1,094.91	$1,094.90	$1,094.90