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	$59.29	10.301%	$65.3975	$65.40	$65.40	$65.40
Purchase #2	$94.67	12.199%	$106.2188	$106.22	$106.20	$106.20
Purchase #3	$100.73	3.180%	$103.9332	$103.93	$103.95	$103.90
Purchase #4	$13.49	4.394%	$14.0828	$14.08	$14.10	$14.10
Purchase #5	$196.92	13.435%	$223.3762	$223.38	$223.40	$223.40
Purchase #6	$12.44	6.145%	$13.2044	$13.20	$13.20	$13.20
Purchase #7	$151.28	11.371%	$168.482	$168.48	$168.50	$168.50
7 purchase totals =	$628.82		$694.6949	$694.69	$694.75	$694.70