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	$215.42	10.377%	$237.7741	$237.77	$237.75	$237.80
Purchase #2	$91.43	4.853%	$95.8671	$95.87	$95.85	$95.90
Purchase #3	$72.33	13.586%	$82.1568	$82.16	$82.15	$82.20
Purchase #4	$245.30	4.164%	$255.5143	$255.51	$255.50	$255.50
Purchase #5	$159.93	4.338%	$166.8678	$166.87	$166.85	$166.90
Purchase #6	$126.56	8.140%	$136.862	$136.86	$136.85	$136.90
Purchase #7	$158.58	10.284%	$174.8884	$174.89	$174.90	$174.90
7 purchase totals =	$1,069.55		$1,149.9305	$1,149.93	$1,149.85	$1,150.10