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	$197.36	6.661%	$210.5061	$210.51	$210.50	$210.50
Purchase #2	$14.48	5.581%	$15.2881	$15.29	$15.30	$15.30
Purchase #3	$180.30	11.288%	$200.6523	$200.65	$200.65	$200.70
Purchase #4	$114.93	11.249%	$127.8585	$127.86	$127.85	$127.90
Purchase #5	$75.50	8.821%	$82.1599	$82.16	$82.15	$82.20
Purchase #6	$204.35	9.835%	$224.4478	$224.45	$224.45	$224.40
Purchase #7	$229.38	11.573%	$255.9261	$255.93	$255.95	$255.90
7 purchase totals =	$1,016.30		$1,116.8388	$1,116.85	$1,116.85	$1,116.90