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	$173.61	10.325%	$191.5352	$191.54	$191.55	$191.50
Purchase #2	$98.72	11.182%	$109.7589	$109.76	$109.75	$109.80
Purchase #3	$90.73	8.107%	$98.0855	$98.09	$98.10	$98.10
Purchase #4	$18.55	5.703%	$19.6079	$19.61	$19.60	$19.60
Purchase #5	$145.65	8.182%	$157.5671	$157.57	$157.55	$157.60
Purchase #6	$241.30	6.390%	$256.7191	$256.72	$256.70	$256.70
Purchase #7	$240.58	8.632%	$261.3469	$261.35	$261.35	$261.30
7 purchase totals =	$1,009.14		$1,094.6206	$1,094.64	$1,094.60	$1,094.60