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	$197.30	8.414%	$213.9008	$213.90	$213.90	$213.90
Purchase #2	$28.37	3.129%	$29.2577	$29.26	$29.25	$29.30
Purchase #3	$185.70	7.379%	$199.4028	$199.40	$199.40	$199.40
Purchase #4	$245.89	6.799%	$262.6081	$262.61	$262.60	$262.60
Purchase #5	$38.36	12.822%	$43.2785	$43.28	$43.30	$43.30
Purchase #6	$215.99	11.623%	$241.0945	$241.09	$241.10	$241.10
Purchase #7	$24.29	12.288%	$27.2748	$27.27	$27.25	$27.30
7 purchase totals =	$935.90		$1,016.8172	$1,016.81	$1,016.80	$1,016.90