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	$208.76	6.782%	$222.9181	$222.92	$222.90	$222.90
Purchase #2	$162.98	7.542%	$175.272	$175.27	$175.25	$175.30
Purchase #3	$156.34	7.238%	$167.6559	$167.66	$167.65	$167.70
Purchase #4	$104.79	13.667%	$119.1116	$119.11	$119.10	$119.10
Purchase #5	$128.60	6.742%	$137.2702	$137.27	$137.25	$137.30
Purchase #6	$205.98	6.626%	$219.6282	$219.63	$219.65	$219.60
Purchase #7	$145.69	6.339%	$154.9253	$154.93	$154.95	$154.90
7 purchase totals =	$1,113.14		$1,196.7813	$1,196.79	$1,196.75	$1,196.80