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	$207.61	7.239%	$222.6389	$222.64	$222.65	$222.60
Purchase #2	$130.47	13.526%	$148.1174	$148.12	$148.10	$148.10
Purchase #3	$60.30	4.196%	$62.8302	$62.83	$62.85	$62.80
Purchase #4	$166.51	4.809%	$174.5175	$174.52	$174.50	$174.50
Purchase #5	$181.94	13.402%	$206.3236	$206.32	$206.30	$206.30
Purchase #6	$94.62	6.438%	$100.7116	$100.71	$100.70	$100.70
Purchase #7	$123.67	13.533%	$140.4063	$140.41	$140.40	$140.40
7 purchase totals =	$965.12		$1,055.5455	$1,055.55	$1,055.50	$1,055.40