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	$59.49	4.811%	$62.3521	$62.35	$62.35	$62.40
Purchase #2	$72.68	8.523%	$78.8745	$78.87	$78.85	$78.90
Purchase #3	$97.94	6.873%	$104.6714	$104.67	$104.65	$104.70
Purchase #4	$225.82	9.591%	$247.4784	$247.48	$247.50	$247.50
Purchase #5	$216.64	12.639%	$244.0211	$244.02	$244.00	$244.00
Purchase #6	$141.76	7.431%	$152.2942	$152.29	$152.30	$152.30
Purchase #7	$203.72	9.634%	$223.3464	$223.35	$223.35	$223.30
7 purchase totals =	$1,018.05		$1,113.0381	$1,113.03	$1,113.00	$1,113.10