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	$87.34	5.491%	$92.1358	$92.14	$92.15	$92.10
Purchase #2	$113.77	7.391%	$122.1787	$122.18	$122.20	$122.20
Purchase #3	$199.46	7.272%	$213.9647	$213.96	$213.95	$214.00
Purchase #4	$150.96	11.862%	$168.8669	$168.87	$168.85	$168.90
Purchase #5	$55.64	10.514%	$61.49	$61.49	$61.50	$61.50
Purchase #6	$144.36	12.252%	$162.047	$162.05	$162.05	$162.00
Purchase #7	$189.86	3.116%	$195.776	$195.78	$195.80	$195.80
7 purchase totals =	$941.39		$1,016.4591	$1,016.47	$1,016.50	$1,016.50