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	$189.26	3.161%	$195.2425	$195.24	$195.25	$195.20
Purchase #2	$173.72	10.505%	$191.9693	$191.97	$191.95	$192.00
Purchase #3	$169.37	13.129%	$191.6066	$191.61	$191.60	$191.60
Purchase #4	$116.31	13.431%	$131.9316	$131.93	$131.95	$131.90
Purchase #5	$164.87	4.671%	$172.5711	$172.57	$172.55	$172.60
Purchase #6	$130.46	10.658%	$144.3644	$144.36	$144.35	$144.40
Purchase #7	$57.78	10.411%	$63.7955	$63.80	$63.80	$63.80
7 purchase totals =	$1,001.77		$1,091.4810	$1,091.48	$1,091.45	$1,091.50