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	$38.85	13.461%	$44.0796	$44.08	$44.10	$44.10
Purchase #2	$72.56	7.752%	$78.1849	$78.18	$78.20	$78.20
Purchase #3	$197.85	6.267%	$210.2493	$210.25	$210.25	$210.20
Purchase #4	$199.74	4.619%	$208.966	$208.97	$208.95	$209.00
Purchase #5	$235.90	9.683%	$258.7422	$258.74	$258.75	$258.70
Purchase #6	$227.68	9.858%	$250.1247	$250.12	$250.10	$250.10
Purchase #7	$43.80	3.869%	$45.4946	$45.49	$45.50	$45.50
7 purchase totals =	$1,016.38		$1,095.8413	$1,095.83	$1,095.85	$1,095.80