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	$89.77	6.346%	$95.4668	$95.47	$95.45	$95.50
Purchase #2	$9.72	6.404%	$10.3425	$10.34	$10.35	$10.30
Purchase #3	$85.82	9.638%	$94.0913	$94.09	$94.10	$94.10
Purchase #4	$95.83	8.444%	$103.9219	$103.92	$103.90	$103.90
Purchase #5	$149.72	5.118%	$157.3827	$157.38	$157.40	$157.40
Purchase #6	$219.34	4.215%	$228.5852	$228.59	$228.60	$228.60
Purchase #7	$75.42	5.459%	$79.5372	$79.54	$79.55	$79.50
7 purchase totals =	$725.62		$769.3276	$769.33	$769.35	$769.30