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	$140.95	3.128%	$145.3589	$145.36	$145.35	$145.40
Purchase #2	$104.52	6.414%	$111.2239	$111.22	$111.20	$111.20
Purchase #3	$112.85	10.613%	$124.8268	$124.83	$124.85	$124.80
Purchase #4	$137.58	6.739%	$146.8515	$146.85	$146.85	$146.90
Purchase #5	$98.89	11.786%	$110.5452	$110.55	$110.55	$110.50
Purchase #6	$245.36	7.330%	$263.3449	$263.34	$263.35	$263.30
Purchase #7	$197.42	8.388%	$213.9796	$213.98	$214.00	$214.00
7 purchase totals =	$1,037.57		$1,116.1308	$1,116.13	$1,116.15	$1,116.10