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	$147.62	8.682%	$160.4364	$160.44	$160.45	$160.40
Purchase #2	$243.94	4.754%	$255.5369	$255.54	$255.55	$255.50
Purchase #3	$176.33	7.775%	$190.0397	$190.04	$190.05	$190.00
Purchase #4	$154.60	11.647%	$172.6063	$172.61	$172.60	$172.60
Purchase #5	$47.65	10.140%	$52.4817	$52.48	$52.50	$52.50
Purchase #6	$142.38	7.371%	$152.8748	$152.87	$152.85	$152.90
Purchase #7	$25.28	4.847%	$26.5053	$26.51	$26.50	$26.50
7 purchase totals =	$937.80		$1,010.4811	$1,010.49	$1,010.50	$1,010.40