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	$185.66	5.448%	$195.7748	$195.77	$195.75	$195.80
Purchase #2	$51.33	8.620%	$55.7546	$55.75	$55.75	$55.80
Purchase #3	$153.92	9.514%	$168.5639	$168.56	$168.55	$168.60
Purchase #4	$121.73	8.195%	$131.7058	$131.71	$131.70	$131.70
Purchase #5	$205.92	3.368%	$212.8554	$212.86	$212.85	$212.90
Purchase #6	$140.81	10.726%	$155.9133	$155.91	$155.90	$155.90
Purchase #7	$84.28	7.401%	$90.5176	$90.52	$90.50	$90.50
7 purchase totals =	$943.65		$1,011.0854	$1,011.08	$1,011.00	$1,011.20