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	$211.83	7.469%	$227.6516	$227.65	$227.65	$227.70
Purchase #2	$160.98	9.667%	$176.5419	$176.54	$176.55	$176.50
Purchase #3	$234.32	13.389%	$265.6931	$265.69	$265.70	$265.70
Purchase #4	$90.65	9.797%	$99.531	$99.53	$99.55	$99.50
Purchase #5	$156.27	3.386%	$161.5613	$161.56	$161.55	$161.60
Purchase #6	$51.40	9.617%	$56.3431	$56.34	$56.35	$56.30
Purchase #7	$118.39	5.259%	$124.6161	$124.62	$124.60	$124.60
7 purchase totals =	$1,023.84		$1,111.9381	$1,111.93	$1,111.95	$1,111.90