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	$89.45	7.128%	$95.826	$95.83	$95.85	$95.80
Purchase #2	$11.72	4.686%	$12.2692	$12.27	$12.25	$12.30
Purchase #3	$186.45	6.813%	$199.1528	$199.15	$199.15	$199.20
Purchase #4	$204.54	9.295%	$223.552	$223.55	$223.55	$223.60
Purchase #5	$237.78	3.440%	$245.9596	$245.96	$245.95	$246.00
Purchase #6	$154.75	11.336%	$172.2925	$172.29	$172.30	$172.30
Purchase #7	$93.61	5.514%	$98.7717	$98.77	$98.75	$98.80
7 purchase totals =	$978.30		$1,047.8238	$1,047.82	$1,047.80	$1,048.00