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	$126.33	5.141%	$132.8246	$132.82	$132.80	$132.80
Purchase #2	$149.86	4.132%	$156.0522	$156.05	$156.05	$156.10
Purchase #3	$217.50	4.378%	$227.0222	$227.02	$227.00	$227.00
Purchase #4	$238.95	10.864%	$264.9095	$264.91	$264.90	$264.90
Purchase #5	$182.75	8.818%	$198.8649	$198.86	$198.85	$198.90
Purchase #6	$128.63	8.498%	$139.561	$139.56	$139.55	$139.60
Purchase #7	$74.54	3.443%	$77.1064	$77.11	$77.10	$77.10
7 purchase totals =	$1,118.56		$1,196.3408	$1,196.33	$1,196.25	$1,196.40