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	$112.73	3.310%	$116.4614	$116.46	$116.45	$116.50
Purchase #2	$98.28	7.606%	$105.7552	$105.76	$105.75	$105.80
Purchase #3	$64.80	3.770%	$67.243	$67.24	$67.25	$67.20
Purchase #4	$73.66	12.543%	$82.8992	$82.90	$82.90	$82.90
Purchase #5	$166.79	9.530%	$182.6851	$182.69	$182.70	$182.70
Purchase #6	$100.88	13.158%	$114.1538	$114.15	$114.15	$114.20
Purchase #7	$196.91	9.738%	$216.0851	$216.09	$216.10	$216.10
7 purchase totals =	$814.05		$885.2828	$885.29	$885.30	$885.40