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	$86.72	5.367%	$91.3743	$91.37	$91.35	$91.40
Purchase #2	$211.42	4.765%	$221.4942	$221.49	$221.50	$221.50
Purchase #3	$209.28	12.806%	$236.0804	$236.08	$236.10	$236.10
Purchase #4	$66.93	3.857%	$69.5115	$69.51	$69.50	$69.50
Purchase #5	$19.60	11.658%	$21.885	$21.89	$21.90	$21.90
Purchase #6	$137.76	6.803%	$147.1318	$147.13	$147.15	$147.10
Purchase #7	$245.69	5.625%	$259.5101	$259.51	$259.50	$259.50
7 purchase totals =	$977.40		$1,046.9873	$1,046.98	$1,047.00	$1,047.00