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	$199.45	6.175%	$211.766	$211.77	$211.75	$211.80
Purchase #2	$185.93	4.545%	$194.3805	$194.38	$194.40	$194.40
Purchase #3	$15.66	11.370%	$17.4405	$17.44	$17.45	$17.40
Purchase #4	$161.36	13.343%	$182.8903	$182.89	$182.90	$182.90
Purchase #5	$243.89	11.572%	$272.113	$272.11	$272.10	$272.10
Purchase #6	$141.65	8.591%	$153.8192	$153.82	$153.80	$153.80
Purchase #7	$71.31	10.266%	$78.6307	$78.63	$78.65	$78.60
7 purchase totals =	$1,019.25		$1,111.0402	$1,111.04	$1,111.05	$1,111.00