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	$187.94	4.587%	$196.5608	$196.56	$196.55	$196.60
Purchase #2	$157.74	4.389%	$164.6632	$164.66	$164.65	$164.70
Purchase #3	$151.90	5.835%	$160.7634	$160.76	$160.75	$160.80
Purchase #4	$162.98	8.352%	$176.5921	$176.59	$176.60	$176.60
Purchase #5	$206.58	3.742%	$214.3102	$214.31	$214.30	$214.30
Purchase #6	$35.43	8.385%	$38.4008	$38.40	$38.40	$38.40
Purchase #7	$95.59	6.868%	$102.1551	$102.16	$102.15	$102.20
7 purchase totals =	$998.16		$1,053.4456	$1,053.44	$1,053.40	$1,053.60