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	$233.58	12.520%	$262.8242	$262.82	$262.80	$262.80
Purchase #2	$73.59	11.569%	$82.1036	$82.10	$82.10	$82.10
Purchase #3	$210.75	5.459%	$222.2548	$222.25	$222.25	$222.30
Purchase #4	$132.82	13.337%	$150.5342	$150.53	$150.55	$150.50
Purchase #5	$71.64	8.216%	$77.5259	$77.53	$77.55	$77.50
Purchase #6	$87.58	9.811%	$96.1725	$96.17	$96.15	$96.20
Purchase #7	$204.76	8.451%	$222.0643	$222.06	$222.05	$222.10
7 purchase totals =	$1,014.72		$1,113.4795	$1,113.46	$1,113.45	$1,113.50