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	$211.91	3.680%	$219.7083	$219.71	$219.70	$219.70
Purchase #2	$179.59	9.484%	$196.6223	$196.62	$196.60	$196.60
Purchase #3	$78.77	3.184%	$81.278	$81.28	$81.30	$81.30
Purchase #4	$96.70	12.544%	$108.83	$108.83	$108.85	$108.80
Purchase #5	$157.92	3.142%	$162.8818	$162.88	$162.90	$162.90
Purchase #6	$130.91	4.687%	$137.0458	$137.05	$137.05	$137.00
Purchase #7	$201.27	8.582%	$218.543	$218.54	$218.55	$218.50
7 purchase totals =	$1,057.07		$1,124.9092	$1,124.91	$1,124.95	$1,124.80