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	$59.37	3.694%	$61.5631	$61.56	$61.55	$61.60
Purchase #2	$80.67	5.369%	$85.0012	$85.00	$85.00	$85.00
Purchase #3	$161.72	8.705%	$175.7977	$175.80	$175.80	$175.80
Purchase #4	$63.98	4.826%	$67.0677	$67.07	$67.05	$67.10
Purchase #5	$207.98	6.717%	$221.95	$221.95	$221.95	$222.00
Purchase #6	$65.62	9.753%	$72.0199	$72.02	$72.00	$72.00
Purchase #7	$119.26	3.465%	$123.3924	$123.39	$123.40	$123.40
7 purchase totals =	$758.60		$806.7920	$806.79	$806.75	$806.90