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	$44.70	4.487%	$46.7057	$46.71	$46.70	$46.70
Purchase #2	$111.70	3.720%	$115.8552	$115.86	$115.85	$115.90
Purchase #3	$56.61	5.796%	$59.8911	$59.89	$59.90	$59.90
Purchase #4	$56.26	9.865%	$61.81	$61.81	$61.80	$61.80
Purchase #5	$208.77	8.860%	$227.267	$227.27	$227.25	$227.30
Purchase #6	$26.87	4.390%	$28.0496	$28.05	$28.05	$28.00
Purchase #7	$202.78	10.335%	$223.7373	$223.74	$223.75	$223.70
7 purchase totals =	$707.69		$763.3159	$763.33	$763.30	$763.30