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	$172.55	13.309%	$195.5147	$195.51	$195.50	$195.50
Purchase #2	$127.86	13.446%	$145.0521	$145.05	$145.05	$145.10
Purchase #3	$190.91	3.126%	$196.8778	$196.88	$196.90	$196.90
Purchase #4	$67.92	4.759%	$71.1523	$71.15	$71.15	$71.20
Purchase #5	$128.90	4.220%	$134.3396	$134.34	$134.35	$134.30
Purchase #6	$147.99	12.162%	$165.9885	$165.99	$166.00	$166.00
Purchase #7	$167.51	13.647%	$190.3701	$190.37	$190.35	$190.40
7 purchase totals =	$1,003.64		$1,099.2951	$1,099.29	$1,099.30	$1,099.40