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	$196.53	9.672%	$215.5384	$215.54	$215.55	$215.50
Purchase #2	$178.31	3.732%	$184.9645	$184.96	$184.95	$185.00
Purchase #3	$211.91	3.842%	$220.0516	$220.05	$220.05	$220.10
Purchase #4	$143.59	8.811%	$156.2417	$156.24	$156.25	$156.20
Purchase #5	$101.93	9.481%	$111.594	$111.59	$111.60	$111.60
Purchase #6	$27.32	3.866%	$28.3762	$28.38	$28.40	$28.40
Purchase #7	$108.85	8.187%	$117.7615	$117.76	$117.75	$117.80
7 purchase totals =	$968.44		$1,034.5279	$1,034.52	$1,034.55	$1,034.60