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	$216.84	7.852%	$233.8663	$233.87	$233.85	$233.90
Purchase #2	$91.77	4.479%	$95.8804	$95.88	$95.90	$95.90
Purchase #3	$186.60	13.813%	$212.3751	$212.38	$212.40	$212.40
Purchase #4	$85.84	4.784%	$89.9466	$89.95	$89.95	$89.90
Purchase #5	$11.60	8.121%	$12.542	$12.54	$12.55	$12.50
Purchase #6	$239.72	10.427%	$264.7156	$264.72	$264.70	$264.70
Purchase #7	$228.83	5.128%	$240.5644	$240.56	$240.55	$240.60
7 purchase totals =	$1,061.20		$1,149.8904	$1,149.90	$1,149.90	$1,149.90