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	$53.96	13.471%	$61.229	$61.23	$61.25	$61.20
Purchase #2	$78.67	11.234%	$87.5078	$87.51	$87.50	$87.50
Purchase #3	$81.56	4.230%	$85.01	$85.01	$85.00	$85.00
Purchase #4	$9.66	6.773%	$10.3143	$10.31	$10.30	$10.30
Purchase #5	$93.54	6.435%	$99.5593	$99.56	$99.55	$99.60
Purchase #6	$99.95	8.289%	$108.2349	$108.23	$108.25	$108.20
Purchase #7	$168.89	4.331%	$176.2046	$176.20	$176.20	$176.20
7 purchase totals =	$586.23		$628.0599	$628.05	$628.05	$628.00