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	$200.40	7.655%	$215.7406	$215.74	$215.75	$215.70
Purchase #2	$71.99	8.517%	$78.1214	$78.12	$78.10	$78.10
Purchase #3	$5.96	5.205%	$6.2702	$6.27	$6.25	$6.30
Purchase #4	$60.92	11.216%	$67.7528	$67.75	$67.75	$67.80
Purchase #5	$85.64	4.723%	$89.6848	$89.68	$89.70	$89.70
Purchase #6	$152.65	6.133%	$162.012	$162.01	$162.00	$162.00
Purchase #7	$42.46	7.341%	$45.577	$45.58	$45.60	$45.60
7 purchase totals =	$620.02		$665.1588	$665.15	$665.15	$665.20