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	$106.36	5.284%	$111.9801	$111.98	$112.00	$112.00
Purchase #2	$58.85	4.452%	$61.47	$61.47	$61.45	$61.50
Purchase #3	$194.81	3.785%	$202.1836	$202.18	$202.20	$202.20
Purchase #4	$241.67	9.134%	$263.7441	$263.74	$263.75	$263.70
Purchase #5	$7.46	3.526%	$7.723	$7.72	$7.70	$7.70
Purchase #6	$42.92	6.232%	$45.5948	$45.59	$45.60	$45.60
Purchase #7	$40.26	5.848%	$42.6144	$42.61	$42.60	$42.60
7 purchase totals =	$692.33		$735.3100	$735.29	$735.30	$735.30