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	$60.80	7.682%	$65.4707	$65.47	$65.45	$65.50
Purchase #2	$159.28	13.188%	$180.2858	$180.29	$180.30	$180.30
Purchase #3	$71.32	13.362%	$80.8498	$80.85	$80.85	$80.80
Purchase #4	$55.29	8.359%	$59.9117	$59.91	$59.90	$59.90
Purchase #5	$76.95	13.230%	$87.1305	$87.13	$87.15	$87.10
Purchase #6	$240.33	5.391%	$253.2862	$253.29	$253.30	$253.30
Purchase #7	$61.25	13.652%	$69.6119	$69.61	$69.60	$69.60
7 purchase totals =	$725.22		$796.5466	$796.55	$796.55	$796.50