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	$66.90	8.162%	$72.3604	$72.36	$72.35	$72.40
Purchase #2	$141.47	4.157%	$147.3509	$147.35	$147.35	$147.40
Purchase #3	$183.40	4.245%	$191.1853	$191.19	$191.20	$191.20
Purchase #4	$203.91	7.464%	$219.1298	$219.13	$219.15	$219.10
Purchase #5	$111.46	7.602%	$119.9332	$119.93	$119.95	$119.90
Purchase #6	$53.72	5.227%	$56.5279	$56.53	$56.55	$56.50
Purchase #7	$230.86	10.828%	$255.8575	$255.86	$255.85	$255.90
7 purchase totals =	$991.72		$1,062.3450	$1,062.35	$1,062.40	$1,062.40