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	$151.45	4.695%	$158.5606	$158.56	$158.55	$158.60
Purchase #2	$40.98	7.481%	$44.0457	$44.05	$44.05	$44.00
Purchase #3	$160.63	7.120%	$172.0669	$172.07	$172.05	$172.10
Purchase #4	$173.88	10.404%	$191.9705	$191.97	$191.95	$192.00
Purchase #5	$37.33	12.126%	$41.8566	$41.86	$41.85	$41.90
Purchase #6	$245.77	9.473%	$269.0518	$269.05	$269.05	$269.10
Purchase #7	$131.68	12.381%	$147.9833	$147.98	$148.00	$148.00
7 purchase totals =	$941.72		$1,025.5354	$1,025.54	$1,025.50	$1,025.70