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	$143.80	12.698%	$162.0597	$162.06	$162.05	$162.10
Purchase #2	$43.63	4.750%	$45.7024	$45.70	$45.70	$45.70
Purchase #3	$80.34	6.460%	$85.53	$85.53	$85.55	$85.50
Purchase #4	$75.85	5.656%	$80.1401	$80.14	$80.15	$80.10
Purchase #5	$59.58	4.421%	$62.214	$62.21	$62.20	$62.20
Purchase #6	$198.63	9.340%	$217.182	$217.18	$217.20	$217.20
Purchase #7	$151.54	13.698%	$172.2979	$172.30	$172.30	$172.30
7 purchase totals =	$753.37		$825.1261	$825.12	$825.15	$825.10