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	$58.84	6.513%	$62.6722	$62.67	$62.65	$62.70
Purchase #2	$75.32	9.301%	$82.3255	$82.33	$82.35	$82.30
Purchase #3	$104.71	3.592%	$108.4712	$108.47	$108.45	$108.50
Purchase #4	$143.84	5.832%	$152.2287	$152.23	$152.25	$152.20
Purchase #5	$64.85	3.549%	$67.1515	$67.15	$67.15	$67.20
Purchase #6	$100.93	4.372%	$105.3427	$105.34	$105.35	$105.30
Purchase #7	$110.61	13.754%	$125.8233	$125.82	$125.80	$125.80
7 purchase totals =	$659.10		$704.0151	$704.01	$704.00	$704.00