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	$162.95	3.116%	$168.0275	$168.03	$168.05	$168.00
Purchase #2	$10.43	13.573%	$11.8457	$11.85	$11.85	$11.80
Purchase #3	$245.48	11.810%	$274.4712	$274.47	$274.45	$274.50
Purchase #4	$24.27	11.691%	$27.1074	$27.11	$27.10	$27.10
Purchase #5	$165.82	11.807%	$185.3984	$185.40	$185.40	$185.40
Purchase #6	$57.95	3.455%	$59.9522	$59.95	$59.95	$60.00
Purchase #7	$156.47	7.151%	$167.6592	$167.66	$167.65	$167.70
7 purchase totals =	$823.37		$894.4616	$894.47	$894.45	$894.50