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	$158.68	8.753%	$172.5693	$172.57	$172.55	$172.60
Purchase #2	$156.41	13.254%	$177.1406	$177.14	$177.15	$177.10
Purchase #3	$72.94	8.398%	$79.0655	$79.07	$79.05	$79.10
Purchase #4	$154.83	12.302%	$173.8772	$173.88	$173.90	$173.90
Purchase #5	$106.34	10.469%	$117.4727	$117.47	$117.45	$117.50
Purchase #6	$28.27	10.756%	$31.3107	$31.31	$31.30	$31.30
Purchase #7	$238.82	10.788%	$264.5839	$264.58	$264.60	$264.60
7 purchase totals =	$916.29		$1,016.0199	$1,016.02	$1,016.00	$1,016.10