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	$77.95	10.838%	$86.3982	$86.40	$86.40	$86.40
Purchase #2	$115.61	9.371%	$126.4438	$126.44	$126.45	$126.40
Purchase #3	$31.89	11.620%	$35.5956	$35.60	$35.60	$35.60
Purchase #4	$40.67	12.803%	$45.877	$45.88	$45.90	$45.90
Purchase #5	$70.27	3.802%	$72.9417	$72.94	$72.95	$72.90
Purchase #6	$29.36	6.347%	$31.2235	$31.22	$31.20	$31.20
Purchase #7	$45.44	10.612%	$50.2621	$50.26	$50.25	$50.30
7 purchase totals =	$411.19		$448.7419	$448.74	$448.75	$448.70