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	$197.37	12.814%	$222.661	$222.66	$222.65	$222.70
Purchase #2	$220.25	6.336%	$234.205	$234.21	$234.20	$234.20
Purchase #3	$37.35	10.402%	$41.2351	$41.24	$41.25	$41.20
Purchase #4	$198.59	6.591%	$211.6791	$211.68	$211.70	$211.70
Purchase #5	$110.83	11.469%	$123.5411	$123.54	$123.55	$123.50
Purchase #6	$82.82	4.724%	$86.7324	$86.73	$86.75	$86.70
Purchase #7	$135.70	13.423%	$153.915	$153.92	$153.90	$153.90
7 purchase totals =	$982.91		$1,073.9687	$1,073.98	$1,074.00	$1,073.90