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	$196.57	13.345%	$222.8023	$222.80	$222.80	$222.80
Purchase #2	$179.65	9.540%	$196.7886	$196.79	$196.80	$196.80
Purchase #3	$189.94	3.165%	$195.9516	$195.95	$195.95	$196.00
Purchase #4	$142.67	11.405%	$158.9415	$158.94	$158.95	$158.90
Purchase #5	$110.95	4.332%	$115.7564	$115.76	$115.75	$115.80
Purchase #6	$133.85	13.422%	$151.8153	$151.82	$151.80	$151.80
Purchase #7	$228.26	4.501%	$238.534	$238.53	$238.55	$238.50
7 purchase totals =	$1,181.89		$1,280.5897	$1,280.59	$1,280.60	$1,280.60