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	$184.25	7.254%	$197.6155	$197.62	$197.60	$197.60
Purchase #2	$207.66	4.306%	$216.6018	$216.60	$216.60	$216.60
Purchase #3	$62.50	5.360%	$65.85	$65.85	$65.85	$65.90
Purchase #4	$20.52	5.250%	$21.5973	$21.60	$21.60	$21.60
Purchase #5	$167.38	10.697%	$185.2846	$185.28	$185.30	$185.30
Purchase #6	$35.82	3.317%	$37.0081	$37.01	$37.00	$37.00
Purchase #7	$68.58	5.627%	$72.439	$72.44	$72.45	$72.40
7 purchase totals =	$746.71		$796.3963	$796.40	$796.40	$796.40