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	$113.73	5.388%	$119.8578	$119.86	$119.85	$119.90
Purchase #2	$155.42	4.722%	$162.7589	$162.76	$162.75	$162.80
Purchase #3	$152.50	5.501%	$160.889	$160.89	$160.90	$160.90
Purchase #4	$137.28	4.567%	$143.5496	$143.55	$143.55	$143.50
Purchase #5	$197.69	3.456%	$204.5222	$204.52	$204.50	$204.50
Purchase #6	$92.53	6.464%	$98.5111	$98.51	$98.50	$98.50
Purchase #7	$138.34	4.131%	$144.0548	$144.05	$144.05	$144.10
7 purchase totals =	$987.49		$1,034.1434	$1,034.14	$1,034.10	$1,034.20