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	$77.98	10.767%	$86.3761	$86.38	$86.40	$86.40
Purchase #2	$173.34	4.178%	$180.5821	$180.58	$180.60	$180.60
Purchase #3	$95.92	9.863%	$105.3806	$105.38	$105.40	$105.40
Purchase #4	$121.51	10.164%	$133.8603	$133.86	$133.85	$133.90
Purchase #5	$185.76	3.484%	$192.2319	$192.23	$192.25	$192.20
Purchase #6	$158.40	13.519%	$179.8141	$179.81	$179.80	$179.80
Purchase #7	$161.42	12.164%	$181.0551	$181.06	$181.05	$181.10
7 purchase totals =	$974.33		$1,059.3002	$1,059.30	$1,059.35	$1,059.40