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	$205.49	6.849%	$219.564	$219.56	$219.55	$219.60
Purchase #2	$189.85	8.115%	$205.2563	$205.26	$205.25	$205.30
Purchase #3	$220.87	10.274%	$243.5622	$243.56	$243.55	$243.60
Purchase #4	$210.42	9.728%	$230.8897	$230.89	$230.90	$230.90
Purchase #5	$51.38	5.797%	$54.3585	$54.36	$54.35	$54.40
Purchase #6	$40.44	12.280%	$45.406	$45.41	$45.40	$45.40
Purchase #7	$32.79	3.343%	$33.8862	$33.89	$33.90	$33.90
7 purchase totals =	$951.24		$1,032.9229	$1,032.93	$1,032.90	$1,033.10