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	$215.65	4.556%	$225.475	$225.48	$225.50	$225.50
Purchase #2	$70.53	11.633%	$78.7348	$78.73	$78.75	$78.70
Purchase #3	$78.27	3.327%	$80.874	$80.87	$80.85	$80.90
Purchase #4	$235.93	13.417%	$267.5847	$267.58	$267.60	$267.60
Purchase #5	$151.98	13.356%	$172.2784	$172.28	$172.30	$172.30
Purchase #6	$250.33	4.148%	$260.7137	$260.71	$260.70	$260.70
Purchase #7	$31.96	3.419%	$33.0527	$33.05	$33.05	$33.10
7 purchase totals =	$1,034.65		$1,118.7133	$1,118.70	$1,118.75	$1,118.80