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	$195.81	5.585%	$206.746	$206.75	$206.75	$206.70
Purchase #2	$216.26	10.460%	$238.8808	$238.88	$238.90	$238.90
Purchase #3	$163.94	6.458%	$174.5272	$174.53	$174.55	$174.50
Purchase #4	$82.67	12.273%	$92.8161	$92.82	$92.80	$92.80
Purchase #5	$222.68	8.810%	$242.2981	$242.30	$242.30	$242.30
Purchase #6	$53.76	10.474%	$59.3908	$59.39	$59.40	$59.40
Purchase #7	$51.60	7.156%	$55.2925	$55.29	$55.30	$55.30
7 purchase totals =	$986.72		$1,069.9515	$1,069.96	$1,070.00	$1,069.90