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	$33.58	4.122%	$34.9642	$34.96	$34.95	$35.00
Purchase #2	$82.52	10.219%	$90.9527	$90.95	$90.95	$91.00
Purchase #3	$224.74	6.293%	$238.8829	$238.88	$238.90	$238.90
Purchase #4	$153.66	9.761%	$168.6588	$168.66	$168.65	$168.70
Purchase #5	$117.73	9.315%	$128.6965	$128.70	$128.70	$128.70
Purchase #6	$158.97	5.537%	$167.7722	$167.77	$167.75	$167.80
Purchase #7	$231.45	10.351%	$255.4074	$255.41	$255.40	$255.40
7 purchase totals =	$1,002.65		$1,085.3347	$1,085.33	$1,085.30	$1,085.50