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	$47.98	10.476%	$53.0064	$53.01	$53.00	$53.00
Purchase #2	$194.83	13.232%	$220.6099	$220.61	$220.60	$220.60
Purchase #3	$179.78	7.116%	$192.5731	$192.57	$192.55	$192.60
Purchase #4	$80.90	13.417%	$91.7544	$91.75	$91.75	$91.80
Purchase #5	$250.80	13.536%	$284.7483	$284.75	$284.75	$284.70
Purchase #6	$145.44	4.417%	$151.8641	$151.86	$151.85	$151.90
Purchase #7	$76.96	10.657%	$85.1616	$85.16	$85.15	$85.20
7 purchase totals =	$976.69		$1,079.7178	$1,079.71	$1,079.65	$1,079.80