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	$182.77	4.311%	$190.6492	$190.65	$190.65	$190.60
Purchase #2	$90.63	10.858%	$100.4706	$100.47	$100.45	$100.50
Purchase #3	$112.48	11.415%	$125.3196	$125.32	$125.30	$125.30
Purchase #4	$125.42	4.158%	$130.635	$130.64	$130.65	$130.60
Purchase #5	$74.32	11.558%	$82.9099	$82.91	$82.90	$82.90
Purchase #6	$214.65	9.806%	$235.6986	$235.70	$235.70	$235.70
Purchase #7	$148.27	11.501%	$165.3225	$165.32	$165.30	$165.30
7 purchase totals =	$948.54		$1,031.0054	$1,031.01	$1,030.95	$1,030.90