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	$211.50	6.175%	$224.5601	$224.56	$224.55	$224.60
Purchase #2	$57.84	7.756%	$62.3261	$62.33	$62.35	$62.30
Purchase #3	$74.79	10.422%	$82.5846	$82.58	$82.60	$82.60
Purchase #4	$103.83	12.607%	$116.9198	$116.92	$116.90	$116.90
Purchase #5	$202.99	6.484%	$216.1519	$216.15	$216.15	$216.20
Purchase #6	$137.37	10.735%	$152.1167	$152.12	$152.10	$152.10
Purchase #7	$188.62	5.594%	$199.1714	$199.17	$199.15	$199.20
7 purchase totals =	$976.94		$1,053.8306	$1,053.83	$1,053.80	$1,053.90