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	$78.81	9.169%	$86.0361	$86.04	$86.05	$86.00
Purchase #2	$176.81	11.352%	$196.8815	$196.88	$196.90	$196.90
Purchase #3	$186.41	4.772%	$195.3055	$195.31	$195.30	$195.30
Purchase #4	$74.28	10.472%	$82.0586	$82.06	$82.05	$82.10
Purchase #5	$124.59	7.247%	$133.619	$133.62	$133.60	$133.60
Purchase #6	$202.98	11.268%	$225.8518	$225.85	$225.85	$225.90
Purchase #7	$117.51	7.723%	$126.5853	$126.59	$126.60	$126.60
7 purchase totals =	$961.39		$1,046.3378	$1,046.35	$1,046.35	$1,046.40