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	$185.81	5.719%	$196.4365	$196.44	$196.45	$196.40
Purchase #2	$59.29	4.552%	$61.9889	$61.99	$62.00	$62.00
Purchase #3	$144.75	13.857%	$164.808	$164.81	$164.80	$164.80
Purchase #4	$115.96	10.835%	$128.5243	$128.52	$128.50	$128.50
Purchase #5	$193.88	10.299%	$213.8477	$213.85	$213.85	$213.80
Purchase #6	$215.35	4.513%	$225.0687	$225.07	$225.05	$225.10
Purchase #7	$126.73	4.515%	$132.4519	$132.45	$132.45	$132.50
7 purchase totals =	$1,041.77		$1,123.1260	$1,123.13	$1,123.10	$1,123.10