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	$201.46	5.220%	$211.9762	$211.98	$212.00	$212.00
Purchase #2	$43.83	10.721%	$48.529	$48.53	$48.55	$48.50
Purchase #3	$111.95	3.111%	$115.4328	$115.43	$115.45	$115.40
Purchase #4	$150.86	6.145%	$160.1303	$160.13	$160.15	$160.10
Purchase #5	$246.27	12.433%	$276.8887	$276.89	$276.90	$276.90
Purchase #6	$162.33	4.469%	$169.5845	$169.58	$169.60	$169.60
Purchase #7	$73.92	10.778%	$81.8871	$81.89	$81.90	$81.90
7 purchase totals =	$990.62		$1,064.4286	$1,064.43	$1,064.55	$1,064.40