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	$87.25	9.731%	$95.7403	$95.74	$95.75	$95.70
Purchase #2	$170.64	12.372%	$191.7516	$191.75	$191.75	$191.80
Purchase #3	$188.56	6.267%	$200.3771	$200.38	$200.40	$200.40
Purchase #4	$178.84	3.550%	$185.1888	$185.19	$185.20	$185.20
Purchase #5	$174.35	3.491%	$180.4366	$180.44	$180.45	$180.40
Purchase #6	$91.27	5.773%	$96.539	$96.54	$96.55	$96.50
Purchase #7	$100.65	12.157%	$112.886	$112.89	$112.90	$112.90
7 purchase totals =	$991.56		$1,062.9194	$1,062.93	$1,063.00	$1,062.90