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	$250.25	4.473%	$261.4437	$261.44	$261.45	$261.40
Purchase #2	$6.33	4.445%	$6.6114	$6.61	$6.60	$6.60
Purchase #3	$85.32	9.569%	$93.4843	$93.48	$93.50	$93.50
Purchase #4	$106.73	5.643%	$112.7528	$112.75	$112.75	$112.80
Purchase #5	$169.66	9.538%	$185.8422	$185.84	$185.85	$185.80
Purchase #6	$26.65	6.738%	$28.4457	$28.45	$28.45	$28.40
Purchase #7	$53.28	10.762%	$59.014	$59.01	$59.00	$59.00
7 purchase totals =	$698.22		$747.5941	$747.58	$747.60	$747.50