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	$191.72	11.615%	$213.9883	$213.99	$214.00	$214.00
Purchase #2	$111.36	11.410%	$124.0662	$124.07	$124.05	$124.10
Purchase #3	$155.47	10.633%	$172.0011	$172.00	$172.00	$172.00
Purchase #4	$133.58	3.104%	$137.7263	$137.73	$137.75	$137.70
Purchase #5	$105.85	3.517%	$109.5727	$109.57	$109.55	$109.60
Purchase #6	$167.97	7.872%	$181.1926	$181.19	$181.20	$181.20
Purchase #7	$55.47	13.304%	$62.8497	$62.85	$62.85	$62.80
7 purchase totals =	$921.42		$1,001.3969	$1,001.40	$1,001.40	$1,001.40