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	$213.86	4.128%	$222.6881	$222.69	$222.70	$222.70
Purchase #2	$106.86	6.574%	$113.885	$113.89	$113.90	$113.90
Purchase #3	$141.88	6.561%	$151.1887	$151.19	$151.20	$151.20
Purchase #4	$206.74	5.610%	$218.3381	$218.34	$218.35	$218.30
Purchase #5	$135.91	5.412%	$143.2654	$143.27	$143.25	$143.30
Purchase #6	$119.35	10.717%	$132.1407	$132.14	$132.15	$132.10
Purchase #7	$157.64	4.279%	$164.3854	$164.39	$164.40	$164.40
7 purchase totals =	$1,082.24		$1,145.8914	$1,145.91	$1,145.95	$1,145.90