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	$200.82	11.260%	$223.4323	$223.43	$223.45	$223.40
Purchase #2	$76.46	6.838%	$81.6883	$81.69	$81.70	$81.70
Purchase #3	$52.83	3.666%	$54.7667	$54.77	$54.75	$54.80
Purchase #4	$206.50	11.600%	$230.454	$230.45	$230.45	$230.50
Purchase #5	$229.25	3.121%	$236.4049	$236.40	$236.40	$236.40
Purchase #6	$42.38	9.617%	$46.4557	$46.46	$46.45	$46.50
Purchase #7	$152.56	10.336%	$168.3286	$168.33	$168.35	$168.30
7 purchase totals =	$960.80		$1,041.5305	$1,041.53	$1,041.55	$1,041.60