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	$222.27	10.420%	$245.4305	$245.43	$245.45	$245.40
Purchase #2	$222.84	12.390%	$250.4499	$250.45	$250.45	$250.40
Purchase #3	$178.62	6.833%	$190.8251	$190.83	$190.85	$190.80
Purchase #4	$202.99	6.601%	$216.3894	$216.39	$216.40	$216.40
Purchase #5	$151.36	7.218%	$162.2852	$162.29	$162.30	$162.30
Purchase #6	$101.58	9.625%	$111.3571	$111.36	$111.35	$111.40
Purchase #7	$120.31	3.853%	$124.9455	$124.95	$124.95	$124.90
7 purchase totals =	$1,199.97		$1,301.6827	$1,301.70	$1,301.75	$1,301.60