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	$95.81	6.126%	$101.6793	$101.68	$101.70	$101.70
Purchase #2	$196.27	6.674%	$209.3691	$209.37	$209.35	$209.40
Purchase #3	$31.60	5.465%	$33.3269	$33.33	$33.35	$33.30
Purchase #4	$90.47	5.604%	$95.5399	$95.54	$95.55	$95.50
Purchase #5	$98.92	6.863%	$105.7089	$105.71	$105.70	$105.70
Purchase #6	$20.34	3.646%	$21.0816	$21.08	$21.10	$21.10
Purchase #7	$193.57	13.756%	$220.1975	$220.20	$220.20	$220.20
7 purchase totals =	$726.98		$786.9032	$786.91	$786.95	$786.90