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	$78.85	7.753%	$84.9632	$84.96	$84.95	$85.00
Purchase #2	$66.80	8.646%	$72.5755	$72.58	$72.60	$72.60
Purchase #3	$52.95	10.770%	$58.6527	$58.65	$58.65	$58.70
Purchase #4	$180.33	6.294%	$191.68	$191.68	$191.70	$191.70
Purchase #5	$160.44	8.387%	$173.8961	$173.90	$173.90	$173.90
Purchase #6	$173.48	6.648%	$185.013	$185.01	$185.00	$185.00
Purchase #7	$235.83	7.298%	$253.0409	$253.04	$253.05	$253.00
7 purchase totals =	$948.68		$1,019.8214	$1,019.82	$1,019.85	$1,019.90