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	$196.70	10.565%	$217.4814	$217.48	$217.50	$217.50
Purchase #2	$33.36	11.103%	$37.064	$37.06	$37.05	$37.10
Purchase #3	$76.56	12.845%	$86.3941	$86.39	$86.40	$86.40
Purchase #4	$167.66	8.623%	$182.1173	$182.12	$182.10	$182.10
Purchase #5	$86.91	4.754%	$91.0417	$91.04	$91.05	$91.00
Purchase #6	$86.66	6.857%	$92.6023	$92.60	$92.60	$92.60
Purchase #7	$35.43	11.109%	$39.3659	$39.37	$39.35	$39.40
7 purchase totals =	$683.28		$746.0667	$746.06	$746.05	$746.10