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	$186.83	5.408%	$196.9338	$196.93	$196.95	$196.90
Purchase #2	$52.59	4.339%	$54.8719	$54.87	$54.85	$54.90
Purchase #3	$238.95	7.372%	$256.5654	$256.57	$256.55	$256.60
Purchase #4	$222.55	7.723%	$239.7375	$239.74	$239.75	$239.70
Purchase #5	$30.82	12.551%	$34.6882	$34.69	$34.70	$34.70
Purchase #6	$67.55	5.464%	$71.2409	$71.24	$71.25	$71.20
Purchase #7	$162.27	11.680%	$181.2231	$181.22	$181.20	$181.20
7 purchase totals =	$961.56		$1,035.2608	$1,035.26	$1,035.25	$1,035.20