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	$81.74	7.330%	$87.7315	$87.73	$87.75	$87.70
Purchase #2	$231.89	5.278%	$244.1292	$244.13	$244.15	$244.10
Purchase #3	$83.95	7.742%	$90.4494	$90.45	$90.45	$90.40
Purchase #4	$145.89	13.611%	$165.7471	$165.75	$165.75	$165.70
Purchase #5	$45.56	9.382%	$49.8344	$49.83	$49.85	$49.80
Purchase #6	$181.77	10.554%	$200.954	$200.95	$200.95	$201.00
Purchase #7	$204.33	5.459%	$215.4844	$215.48	$215.50	$215.50
7 purchase totals =	$975.13		$1,054.3300	$1,054.32	$1,054.40	$1,054.20