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	$97.63	7.869%	$105.3125	$105.31	$105.30	$105.30
Purchase #2	$140.90	8.520%	$152.9047	$152.90	$152.90	$152.90
Purchase #3	$91.50	5.395%	$96.4364	$96.44	$96.45	$96.40
Purchase #4	$152.47	5.414%	$160.7247	$160.72	$160.70	$160.70
Purchase #5	$223.75	10.481%	$247.2012	$247.20	$247.20	$247.20
Purchase #6	$36.59	10.568%	$40.4568	$40.46	$40.45	$40.50
Purchase #7	$201.97	5.416%	$212.9087	$212.91	$212.90	$212.90
7 purchase totals =	$944.81		$1,015.9450	$1,015.94	$1,015.90	$1,015.90