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	$58.46	6.849%	$62.4639	$62.46	$62.45	$62.50
Purchase #2	$78.35	4.233%	$81.6666	$81.67	$81.65	$81.70
Purchase #3	$145.73	3.357%	$150.6222	$150.62	$150.60	$150.60
Purchase #4	$208.27	7.163%	$223.1884	$223.19	$223.20	$223.20
Purchase #5	$63.94	12.407%	$71.873	$71.87	$71.85	$71.90
Purchase #6	$72.55	7.646%	$78.0972	$78.10	$78.10	$78.10
Purchase #7	$219.96	7.437%	$236.3184	$236.32	$236.30	$236.30
7 purchase totals =	$847.26		$904.2297	$904.23	$904.15	$904.30