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	$229.85	7.391%	$246.8382	$246.84	$246.85	$246.80
Purchase #2	$230.46	12.767%	$259.8828	$259.88	$259.90	$259.90
Purchase #3	$210.60	11.414%	$234.6379	$234.64	$234.65	$234.60
Purchase #4	$249.53	8.769%	$271.4113	$271.41	$271.40	$271.40
Purchase #5	$69.98	4.214%	$72.929	$72.93	$72.95	$72.90
Purchase #6	$209.69	6.106%	$222.4937	$222.49	$222.50	$222.50
Purchase #7	$75.63	3.432%	$78.2256	$78.23	$78.25	$78.20
7 purchase totals =	$1,275.74		$1,386.4185	$1,386.42	$1,386.50	$1,386.30