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	$102.52	11.612%	$114.4246	$114.42	$114.40	$114.40
Purchase #2	$202.73	3.831%	$210.4966	$210.50	$210.50	$210.50
Purchase #3	$12.36	9.674%	$13.5557	$13.56	$13.55	$13.60
Purchase #4	$181.27	6.413%	$192.8948	$192.89	$192.90	$192.90
Purchase #5	$101.32	8.157%	$109.5847	$109.58	$109.60	$109.60
Purchase #6	$104.35	9.816%	$114.593	$114.59	$114.60	$114.60
Purchase #7	$18.37	12.450%	$20.6571	$20.66	$20.65	$20.70
7 purchase totals =	$722.92		$776.2065	$776.20	$776.20	$776.30