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	$59.72	10.319%	$65.8825	$65.88	$65.90	$65.90
Purchase #2	$180.48	11.161%	$200.6234	$200.62	$200.60	$200.60
Purchase #3	$233.45	4.585%	$244.1537	$244.15	$244.15	$244.20
Purchase #4	$21.76	4.855%	$22.8164	$22.82	$22.80	$22.80
Purchase #5	$184.66	4.666%	$193.2762	$193.28	$193.30	$193.30
Purchase #6	$184.72	8.528%	$200.4729	$200.47	$200.45	$200.50
Purchase #7	$155.53	7.334%	$166.9366	$166.94	$166.95	$166.90
7 purchase totals =	$1,020.32		$1,094.1617	$1,094.16	$1,094.15	$1,094.20