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	$82.93	3.658%	$85.9636	$85.96	$85.95	$86.00
Purchase #2	$177.50	6.235%	$188.5671	$188.57	$188.55	$188.60
Purchase #3	$189.91	4.665%	$198.7693	$198.77	$198.75	$198.80
Purchase #4	$188.67	10.666%	$208.7935	$208.79	$208.80	$208.80
Purchase #5	$86.67	8.645%	$94.1626	$94.16	$94.15	$94.20
Purchase #6	$161.40	13.622%	$183.3859	$183.39	$183.40	$183.40
Purchase #7	$50.41	12.342%	$56.6316	$56.63	$56.65	$56.60
7 purchase totals =	$937.49		$1,016.2736	$1,016.27	$1,016.25	$1,016.40