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	$148.61	12.791%	$167.6187	$167.62	$167.60	$167.60
Purchase #2	$42.39	7.512%	$45.5743	$45.57	$45.55	$45.60
Purchase #3	$141.50	11.753%	$158.1305	$158.13	$158.15	$158.10
Purchase #4	$87.30	3.502%	$90.3572	$90.36	$90.35	$90.40
Purchase #5	$93.37	9.344%	$102.0945	$102.09	$102.10	$102.10
Purchase #6	$80.43	7.322%	$86.3191	$86.32	$86.30	$86.30
Purchase #7	$78.42	5.647%	$82.8484	$82.85	$82.85	$82.80
7 purchase totals =	$672.02		$732.9427	$732.94	$732.90	$732.90