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	$108.41	7.867%	$116.9386	$116.94	$116.95	$116.90
Purchase #2	$182.67	13.655%	$207.6136	$207.61	$207.60	$207.60
Purchase #3	$239.34	10.629%	$264.7794	$264.78	$264.80	$264.80
Purchase #4	$181.75	7.865%	$196.0446	$196.04	$196.05	$196.00
Purchase #5	$99.44	13.562%	$112.9261	$112.93	$112.95	$112.90
Purchase #6	$161.87	11.518%	$180.5142	$180.51	$180.50	$180.50
Purchase #7	$101.67	3.768%	$105.5009	$105.50	$105.50	$105.50
7 purchase totals =	$1,075.15		$1,184.3174	$1,184.31	$1,184.35	$1,184.20