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	$111.69	4.807%	$117.0589	$117.06	$117.05	$117.10
Purchase #2	$67.27	7.535%	$72.3388	$72.34	$72.35	$72.30
Purchase #3	$138.41	5.749%	$146.3672	$146.37	$146.35	$146.40
Purchase #4	$158.71	8.256%	$171.8131	$171.81	$171.80	$171.80
Purchase #5	$178.41	7.500%	$191.7908	$191.79	$191.80	$191.80
Purchase #6	$185.74	4.721%	$194.5088	$194.51	$194.50	$194.50
Purchase #7	$229.66	10.806%	$254.4771	$254.48	$254.50	$254.50
7 purchase totals =	$1,069.89		$1,148.3547	$1,148.36	$1,148.35	$1,148.40