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	$56.78	7.516%	$61.0476	$61.05	$61.05	$61.00
Purchase #2	$226.34	10.808%	$250.8028	$250.80	$250.80	$250.80
Purchase #3	$165.52	9.713%	$181.597	$181.60	$181.60	$181.60
Purchase #4	$70.70	4.816%	$74.1049	$74.10	$74.10	$74.10
Purchase #5	$61.37	5.275%	$64.6073	$64.61	$64.60	$64.60
Purchase #6	$142.97	5.208%	$150.4159	$150.42	$150.40	$150.40
Purchase #7	$204.32	8.638%	$221.9692	$221.97	$221.95	$222.00
7 purchase totals =	$928.00		$1,004.5447	$1,004.55	$1,004.50	$1,004.50