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	$198.61	10.514%	$219.4919	$219.49	$219.50	$219.50
Purchase #2	$51.40	6.429%	$54.7045	$54.70	$54.70	$54.70
Purchase #3	$197.98	7.378%	$212.587	$212.59	$212.60	$212.60
Purchase #4	$35.83	3.260%	$36.9981	$37.00	$37.00	$37.00
Purchase #5	$194.69	11.528%	$217.1339	$217.13	$217.15	$217.10
Purchase #6	$246.50	7.103%	$264.0089	$264.01	$264.00	$264.00
Purchase #7	$13.61	7.334%	$14.6082	$14.61	$14.60	$14.60
7 purchase totals =	$938.62		$1,019.5325	$1,019.53	$1,019.55	$1,019.50