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	$181.64	7.642%	$195.5209	$195.52	$195.50	$195.50
Purchase #2	$220.73	8.248%	$238.9358	$238.94	$238.95	$238.90
Purchase #3	$10.40	11.804%	$11.6276	$11.63	$11.65	$11.60
Purchase #4	$109.28	13.405%	$123.929	$123.93	$123.95	$123.90
Purchase #5	$100.74	12.778%	$113.6126	$113.61	$113.60	$113.60
Purchase #6	$214.42	7.138%	$229.7253	$229.73	$229.75	$229.70
Purchase #7	$91.41	8.435%	$99.1204	$99.12	$99.10	$99.10
7 purchase totals =	$928.62		$1,012.4716	$1,012.48	$1,012.50	$1,012.30