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	$57.30	4.600%	$59.9358	$59.94	$59.95	$59.90
Purchase #2	$246.98	4.617%	$258.3831	$258.38	$258.40	$258.40
Purchase #3	$111.37	3.526%	$115.2969	$115.30	$115.30	$115.30
Purchase #4	$173.65	4.859%	$182.0877	$182.09	$182.10	$182.10
Purchase #5	$167.64	12.576%	$188.7224	$188.72	$188.70	$188.70
Purchase #6	$28.62	11.674%	$31.9611	$31.96	$31.95	$32.00
Purchase #7	$199.79	12.554%	$224.8716	$224.87	$224.85	$224.90
7 purchase totals =	$985.35		$1,061.2586	$1,061.26	$1,061.25	$1,061.30