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	$59.37	3.688%	$61.5596	$61.56	$61.55	$61.60
Purchase #2	$61.34	5.756%	$64.8707	$64.87	$64.85	$64.90
Purchase #3	$172.31	5.215%	$181.296	$181.30	$181.30	$181.30
Purchase #4	$169.31	11.746%	$189.1972	$189.20	$189.20	$189.20
Purchase #5	$222.55	6.688%	$237.4341	$237.43	$237.45	$237.40
Purchase #6	$92.67	13.833%	$105.489	$105.49	$105.50	$105.50
Purchase #7	$217.94	7.138%	$233.4966	$233.50	$233.50	$233.50
7 purchase totals =	$995.49		$1,073.3432	$1,073.35	$1,073.35	$1,073.40