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	$215.57	7.744%	$232.2637	$232.26	$232.25	$232.30
Purchase #2	$195.72	7.639%	$210.6711	$210.67	$210.65	$210.70
Purchase #3	$43.40	7.153%	$46.5044	$46.50	$46.50	$46.50
Purchase #4	$11.65	4.440%	$12.1673	$12.17	$12.15	$12.20
Purchase #5	$37.42	8.394%	$40.561	$40.56	$40.55	$40.60
Purchase #6	$85.91	5.800%	$90.8928	$90.89	$90.90	$90.90
Purchase #7	$37.65	4.391%	$39.3032	$39.30	$39.30	$39.30
7 purchase totals =	$627.32		$672.3635	$672.35	$672.30	$672.50