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	$195.34	9.483%	$213.8641	$213.86	$213.85	$213.90
Purchase #2	$111.89	4.137%	$116.5189	$116.52	$116.50	$116.50
Purchase #3	$89.65	13.730%	$101.9589	$101.96	$101.95	$102.00
Purchase #4	$204.64	13.289%	$231.8346	$231.83	$231.85	$231.80
Purchase #5	$164.83	4.425%	$172.1237	$172.12	$172.10	$172.10
Purchase #6	$243.58	5.146%	$256.1146	$256.11	$256.10	$256.10
Purchase #7	$162.48	3.177%	$167.642	$167.64	$167.65	$167.60
7 purchase totals =	$1,172.41		$1,260.0568	$1,260.04	$1,260.00	$1,260.00