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	$132.39	10.387%	$146.1413	$146.14	$146.15	$146.10
Purchase #2	$53.84	4.374%	$56.195	$56.20	$56.20	$56.20
Purchase #3	$198.88	6.646%	$212.0976	$212.10	$212.10	$212.10
Purchase #4	$78.29	5.481%	$82.5811	$82.58	$82.60	$82.60
Purchase #5	$218.96	4.645%	$229.1307	$229.13	$229.15	$229.10
Purchase #6	$150.74	11.608%	$168.2379	$168.24	$168.25	$168.20
Purchase #7	$135.79	10.840%	$150.5096	$150.51	$150.50	$150.50
7 purchase totals =	$968.89		$1,044.8932	$1,044.90	$1,044.95	$1,044.80