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	$118.49	6.715%	$126.4466	$126.45	$126.45	$126.40
Purchase #2	$189.73	10.525%	$209.6991	$209.70	$209.70	$209.70
Purchase #3	$188.85	13.479%	$214.3051	$214.31	$214.30	$214.30
Purchase #4	$190.43	3.418%	$196.9389	$196.94	$196.95	$196.90
Purchase #5	$104.32	6.607%	$111.2124	$111.21	$111.20	$111.20
Purchase #6	$248.89	7.177%	$266.7528	$266.75	$266.75	$266.80
Purchase #7	$72.72	6.520%	$77.4613	$77.46	$77.45	$77.50
7 purchase totals =	$1,113.43		$1,202.8162	$1,202.82	$1,202.80	$1,202.80