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	$143.52	5.258%	$151.0663	$151.07	$151.05	$151.10
Purchase #2	$61.87	3.714%	$64.1679	$64.17	$64.15	$64.20
Purchase #3	$110.82	7.502%	$119.1337	$119.13	$119.15	$119.10
Purchase #4	$186.82	9.670%	$204.8855	$204.89	$204.90	$204.90
Purchase #5	$159.26	9.466%	$174.3356	$174.34	$174.35	$174.30
Purchase #6	$181.93	7.807%	$196.1333	$196.13	$196.15	$196.10
Purchase #7	$109.56	8.598%	$118.98	$118.98	$119.00	$119.00
7 purchase totals =	$953.78		$1,028.7023	$1,028.71	$1,028.75	$1,028.70