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	$135.29	4.544%	$141.4376	$141.44	$141.45	$141.40
Purchase #2	$233.67	10.339%	$257.8291	$257.83	$257.85	$257.80
Purchase #3	$176.97	11.263%	$196.9021	$196.90	$196.90	$196.90
Purchase #4	$28.58	3.467%	$29.5709	$29.57	$29.55	$29.60
Purchase #5	$229.71	11.582%	$256.315	$256.32	$256.30	$256.30
Purchase #6	$51.98	7.849%	$56.0599	$56.06	$56.05	$56.10
Purchase #7	$67.82	12.261%	$76.1354	$76.14	$76.15	$76.10
7 purchase totals =	$924.02		$1,014.2500	$1,014.26	$1,014.25	$1,014.20