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	$87.43	8.811%	$95.1335	$95.13	$95.15	$95.10
Purchase #2	$221.78	10.234%	$244.477	$244.48	$244.50	$244.50
Purchase #3	$241.62	5.347%	$254.5394	$254.54	$254.55	$254.50
Purchase #4	$79.32	12.312%	$89.0859	$89.09	$89.10	$89.10
Purchase #5	$56.36	9.750%	$61.8551	$61.86	$61.85	$61.90
Purchase #6	$210.27	6.768%	$224.5011	$224.50	$224.50	$224.50
Purchase #7	$133.65	9.712%	$146.6301	$146.63	$146.65	$146.60
7 purchase totals =	$1,030.43		$1,116.2221	$1,116.23	$1,116.30	$1,116.20