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	$157.72	9.235%	$172.2854	$172.29	$172.30	$172.30
Purchase #2	$169.85	9.383%	$185.787	$185.79	$185.80	$185.80
Purchase #3	$141.46	7.729%	$152.3934	$152.39	$152.40	$152.40
Purchase #4	$106.77	8.132%	$115.4525	$115.45	$115.45	$115.50
Purchase #5	$56.81	5.494%	$59.9311	$59.93	$59.95	$59.90
Purchase #6	$179.47	9.363%	$196.2738	$196.27	$196.25	$196.30
Purchase #7	$212.88	4.575%	$222.6193	$222.62	$222.60	$222.60
7 purchase totals =	$1,024.96		$1,104.7425	$1,104.74	$1,104.75	$1,104.80