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	$218.89	6.665%	$233.479	$233.48	$233.50	$233.50
Purchase #2	$207.77	5.431%	$219.054	$219.05	$219.05	$219.10
Purchase #3	$217.58	6.151%	$230.9633	$230.96	$230.95	$231.00
Purchase #4	$38.82	7.690%	$41.8053	$41.81	$41.80	$41.80
Purchase #5	$57.46	7.206%	$61.6006	$61.60	$61.60	$61.60
Purchase #6	$238.53	6.117%	$253.1209	$253.12	$253.10	$253.10
Purchase #7	$173.27	5.369%	$182.5729	$182.57	$182.55	$182.60
7 purchase totals =	$1,152.32		$1,222.5960	$1,222.59	$1,222.55	$1,222.70