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	$93.27	5.124%	$98.0492	$98.05	$98.05	$98.00
Purchase #2	$42.55	5.508%	$44.8937	$44.89	$44.90	$44.90
Purchase #3	$163.85	5.136%	$172.2653	$172.27	$172.25	$172.30
Purchase #4	$112.64	12.731%	$126.9802	$126.98	$127.00	$127.00
Purchase #5	$211.90	12.287%	$237.9362	$237.94	$237.95	$237.90
Purchase #6	$185.60	12.256%	$208.3471	$208.35	$208.35	$208.30
Purchase #7	$207.29	3.516%	$214.5783	$214.58	$214.60	$214.60
7 purchase totals =	$1,017.10		$1,103.0500	$1,103.06	$1,103.10	$1,103.00