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	$72.79	5.707%	$76.9441	$76.94	$76.95	$76.90
Purchase #2	$31.62	5.863%	$33.4739	$33.47	$33.45	$33.50
Purchase #3	$239.56	13.790%	$272.5953	$272.60	$272.60	$272.60
Purchase #4	$176.46	11.811%	$197.3017	$197.30	$197.30	$197.30
Purchase #5	$99.28	12.460%	$111.6503	$111.65	$111.65	$111.70
Purchase #6	$65.85	4.703%	$68.9469	$68.95	$68.95	$68.90
Purchase #7	$243.27	5.405%	$256.4187	$256.42	$256.40	$256.40
7 purchase totals =	$928.83		$1,017.3309	$1,017.33	$1,017.30	$1,017.30