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	$149.34	11.249%	$166.1393	$166.14	$166.15	$166.10
Purchase #2	$9.91	9.298%	$10.8314	$10.83	$10.85	$10.80
Purchase #3	$205.44	4.664%	$215.0217	$215.02	$215.00	$215.00
Purchase #4	$99.76	10.166%	$109.9016	$109.90	$109.90	$109.90
Purchase #5	$66.50	9.716%	$72.9611	$72.96	$72.95	$73.00
Purchase #6	$41.85	4.120%	$43.5742	$43.57	$43.55	$43.60
Purchase #7	$81.82	13.614%	$92.959	$92.96	$92.95	$93.00
7 purchase totals =	$654.62		$711.3883	$711.38	$711.35	$711.40