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	$198.36	3.405%	$205.1142	$205.11	$205.10	$205.10
Purchase #2	$141.80	7.147%	$151.9344	$151.93	$151.95	$151.90
Purchase #3	$231.44	5.459%	$244.0743	$244.07	$244.05	$244.10
Purchase #4	$45.59	6.570%	$48.5853	$48.59	$48.60	$48.60
Purchase #5	$188.78	4.683%	$197.6206	$197.62	$197.60	$197.60
Purchase #6	$91.42	11.530%	$101.9607	$101.96	$101.95	$102.00
Purchase #7	$57.73	3.762%	$59.9018	$59.90	$59.90	$59.90
7 purchase totals =	$955.12		$1,009.1913	$1,009.18	$1,009.15	$1,009.20