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	$151.98	11.560%	$169.5489	$169.55	$169.55	$169.50
Purchase #2	$20.94	9.131%	$22.852	$22.85	$22.85	$22.90
Purchase #3	$154.78	12.342%	$173.8829	$173.88	$173.90	$173.90
Purchase #4	$223.33	12.213%	$250.6053	$250.61	$250.60	$250.60
Purchase #5	$170.48	5.510%	$179.8734	$179.87	$179.85	$179.90
Purchase #6	$191.53	3.276%	$197.8045	$197.80	$197.80	$197.80
Purchase #7	$62.82	6.264%	$66.755	$66.76	$66.75	$66.80
7 purchase totals =	$975.86		$1,061.3220	$1,061.32	$1,061.30	$1,061.40