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	$213.85	6.718%	$228.2164	$228.22	$228.20	$228.20
Purchase #2	$235.79	10.415%	$260.3475	$260.35	$260.35	$260.30
Purchase #3	$51.48	5.854%	$54.4936	$54.49	$54.50	$54.50
Purchase #4	$55.61	10.350%	$61.3656	$61.37	$61.35	$61.40
Purchase #5	$125.71	13.699%	$142.931	$142.93	$142.95	$142.90
Purchase #6	$209.98	5.355%	$221.2244	$221.22	$221.20	$221.20
Purchase #7	$47.64	6.562%	$50.7661	$50.77	$50.75	$50.80
7 purchase totals =	$940.06		$1,019.3446	$1,019.35	$1,019.30	$1,019.30