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	$93.48	3.191%	$96.4629	$96.46	$96.45	$96.50
Purchase #2	$10.48	8.333%	$11.3533	$11.35	$11.35	$11.40
Purchase #3	$149.43	12.610%	$168.2731	$168.27	$168.25	$168.30
Purchase #4	$226.33	5.849%	$239.568	$239.57	$239.55	$239.60
Purchase #5	$10.41	6.524%	$11.0891	$11.09	$11.10	$11.10
Purchase #6	$218.94	4.868%	$229.598	$229.60	$229.60	$229.60
Purchase #7	$37.53	6.450%	$39.9507	$39.95	$39.95	$40.00
7 purchase totals =	$746.60		$796.2951	$796.29	$796.25	$796.50