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	$48.51	7.367%	$52.0837	$52.08	$52.10	$52.10
Purchase #2	$93.82	6.473%	$99.893	$99.89	$99.90	$99.90
Purchase #3	$6.50	4.406%	$6.7864	$6.79	$6.80	$6.80
Purchase #4	$59.52	9.440%	$65.1387	$65.14	$65.15	$65.10
Purchase #5	$110.42	8.646%	$119.9669	$119.97	$119.95	$120.00
Purchase #6	$53.46	6.199%	$56.774	$56.77	$56.75	$56.80
Purchase #7	$59.93	9.197%	$65.4418	$65.44	$65.45	$65.40
7 purchase totals =	$432.16		$466.0845	$466.08	$466.10	$466.10