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	$68.47	8.196%	$74.0818	$74.08	$74.10	$74.10
Purchase #2	$227.70	11.537%	$253.9697	$253.97	$253.95	$254.00
Purchase #3	$199.47	7.564%	$214.5579	$214.56	$214.55	$214.60
Purchase #4	$101.28	5.535%	$106.8858	$106.89	$106.90	$106.90
Purchase #5	$137.41	10.620%	$152.0029	$152.00	$152.00	$152.00
Purchase #6	$90.79	4.545%	$94.9164	$94.92	$94.90	$94.90
Purchase #7	$116.74	9.188%	$127.4661	$127.47	$127.45	$127.50
7 purchase totals =	$941.86		$1,023.8806	$1,023.89	$1,023.85	$1,024.00