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	$191.88	11.489%	$213.9251	$213.93	$213.95	$213.90
Purchase #2	$172.87	11.543%	$192.8244	$192.82	$192.80	$192.80
Purchase #3	$181.64	9.183%	$198.32	$198.32	$198.30	$198.30
Purchase #4	$78.47	11.438%	$87.4454	$87.45	$87.45	$87.40
Purchase #5	$9.43	6.869%	$10.0777	$10.08	$10.10	$10.10
Purchase #6	$103.96	5.144%	$109.3077	$109.31	$109.30	$109.30
Purchase #7	$82.85	3.518%	$85.7647	$85.76	$85.75	$85.80
7 purchase totals =	$821.10		$897.6650	$897.67	$897.65	$897.60