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	$189.66	3.265%	$195.8524	$195.85	$195.85	$195.90
Purchase #2	$89.75	13.623%	$101.9766	$101.98	$102.00	$102.00
Purchase #3	$214.58	13.550%	$243.6556	$243.66	$243.65	$243.70
Purchase #4	$29.82	11.119%	$33.1357	$33.14	$33.15	$33.10
Purchase #5	$140.72	5.776%	$148.848	$148.85	$148.85	$148.80
Purchase #6	$119.56	6.765%	$127.6482	$127.65	$127.65	$127.60
Purchase #7	$59.88	7.116%	$64.1411	$64.14	$64.15	$64.10
7 purchase totals =	$843.97		$915.2576	$915.27	$915.30	$915.20