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	$167.92	7.534%	$180.5711	$180.57	$180.55	$180.60
Purchase #2	$30.55	10.761%	$33.8375	$33.84	$33.85	$33.80
Purchase #3	$29.89	4.166%	$31.1352	$31.14	$31.15	$31.10
Purchase #4	$93.60	7.443%	$100.5666	$100.57	$100.55	$100.60
Purchase #5	$141.82	4.805%	$148.6345	$148.63	$148.65	$148.60
Purchase #6	$184.98	6.574%	$197.1406	$197.14	$197.15	$197.10
Purchase #7	$36.91	8.711%	$40.1252	$40.13	$40.15	$40.10
7 purchase totals =	$685.67		$732.0107	$732.02	$732.05	$731.90