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	$71.61	9.149%	$78.1616	$78.16	$78.15	$78.20
Purchase #2	$17.75	6.327%	$18.873	$18.87	$18.85	$18.90
Purchase #3	$149.79	7.700%	$161.3238	$161.32	$161.30	$161.30
Purchase #4	$142.95	13.515%	$162.2697	$162.27	$162.25	$162.30
Purchase #5	$205.28	4.155%	$213.8094	$213.81	$213.80	$213.80
Purchase #6	$200.45	8.560%	$217.6085	$217.61	$217.60	$217.60
Purchase #7	$184.39	6.404%	$196.1983	$196.20	$196.20	$196.20
7 purchase totals =	$972.22		$1,048.2443	$1,048.24	$1,048.15	$1,048.30