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	$195.98	6.680%	$209.0715	$209.07	$209.05	$209.10
Purchase #2	$217.56	6.457%	$231.6078	$231.61	$231.60	$231.60
Purchase #3	$219.60	3.715%	$227.7581	$227.76	$227.75	$227.80
Purchase #4	$109.32	8.584%	$118.704	$118.70	$118.70	$118.70
Purchase #5	$57.74	3.705%	$59.8793	$59.88	$59.90	$59.90
Purchase #6	$65.61	9.124%	$71.5963	$71.60	$71.60	$71.60
Purchase #7	$220.37	7.126%	$236.0736	$236.07	$236.05	$236.10
7 purchase totals =	$1,086.18		$1,154.6906	$1,154.69	$1,154.65	$1,154.80