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	$200.51	6.548%	$213.6394	$213.64	$213.65	$213.60
Purchase #2	$19.62	6.758%	$20.9459	$20.95	$20.95	$20.90
Purchase #3	$222.57	10.767%	$246.5341	$246.53	$246.55	$246.50
Purchase #4	$136.80	7.287%	$146.7686	$146.77	$146.75	$146.80
Purchase #5	$99.28	12.527%	$111.7168	$111.72	$111.70	$111.70
Purchase #6	$164.54	7.517%	$176.9085	$176.91	$176.90	$176.90
Purchase #7	$118.29	13.372%	$134.1077	$134.11	$134.10	$134.10
7 purchase totals =	$961.61		$1,050.6210	$1,050.63	$1,050.60	$1,050.50