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	$213.46	6.485%	$227.3029	$227.30	$227.30	$227.30
Purchase #2	$43.88	5.392%	$46.246	$46.25	$46.25	$46.20
Purchase #3	$210.87	13.619%	$239.5884	$239.59	$239.60	$239.60
Purchase #4	$71.72	9.432%	$78.4846	$78.48	$78.50	$78.50
Purchase #5	$213.89	5.695%	$226.071	$226.07	$226.05	$226.10
Purchase #6	$45.68	4.652%	$47.805	$47.81	$47.80	$47.80
Purchase #7	$195.89	12.111%	$219.6142	$219.61	$219.60	$219.60
7 purchase totals =	$995.39		$1,085.1121	$1,085.11	$1,085.10	$1,085.10