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	$193.86	11.689%	$216.5203	$216.52	$216.50	$216.50
Purchase #2	$59.86	4.378%	$62.4807	$62.48	$62.50	$62.50
Purchase #3	$242.69	3.482%	$251.1405	$251.14	$251.15	$251.10
Purchase #4	$92.63	10.212%	$102.0894	$102.09	$102.10	$102.10
Purchase #5	$238.78	10.517%	$263.8925	$263.89	$263.90	$263.90
Purchase #6	$111.35	12.337%	$125.0872	$125.09	$125.10	$125.10
Purchase #7	$85.39	7.556%	$91.8421	$91.84	$91.85	$91.80
7 purchase totals =	$1,024.56		$1,113.0527	$1,113.05	$1,113.10	$1,113.00