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	$94.48	6.841%	$100.9434	$100.94	$100.95	$100.90
Purchase #2	$200.38	5.489%	$211.3789	$211.38	$211.40	$211.40
Purchase #3	$18.50	3.238%	$19.099	$19.10	$19.10	$19.10
Purchase #4	$37.82	7.610%	$40.6981	$40.70	$40.70	$40.70
Purchase #5	$111.83	11.534%	$124.7285	$124.73	$124.75	$124.70
Purchase #6	$156.34	6.219%	$166.0628	$166.06	$166.05	$166.10
Purchase #7	$85.50	4.205%	$89.0953	$89.10	$89.10	$89.10
7 purchase totals =	$704.85		$752.0060	$752.01	$752.05	$752.00