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	$185.80	11.361%	$206.9087	$206.91	$206.90	$206.90
Purchase #2	$172.36	10.784%	$190.9473	$190.95	$190.95	$190.90
Purchase #3	$43.56	13.807%	$49.5743	$49.57	$49.55	$49.60
Purchase #4	$184.48	6.313%	$196.1262	$196.13	$196.15	$196.10
Purchase #5	$247.87	9.857%	$272.3025	$272.30	$272.30	$272.30
Purchase #6	$213.63	4.276%	$222.7648	$222.76	$222.75	$222.80
Purchase #7	$208.33	9.702%	$228.5422	$228.54	$228.55	$228.50
7 purchase totals =	$1,256.03		$1,367.1660	$1,367.16	$1,367.15	$1,367.10