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	$172.28	13.790%	$196.0374	$196.04	$196.05	$196.00
Purchase #2	$171.65	8.653%	$186.5029	$186.50	$186.50	$186.50
Purchase #3	$202.62	13.452%	$229.8764	$229.88	$229.90	$229.90
Purchase #4	$238.84	6.633%	$254.6823	$254.68	$254.70	$254.70
Purchase #5	$108.86	11.271%	$121.1296	$121.13	$121.15	$121.10
Purchase #6	$39.89	11.733%	$44.5703	$44.57	$44.55	$44.60
Purchase #7	$209.46	6.752%	$223.6027	$223.60	$223.60	$223.60
7 purchase totals =	$1,143.60		$1,256.4016	$1,256.40	$1,256.45	$1,256.40