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	$118.90	10.323%	$131.174	$131.17	$131.15	$131.20
Purchase #2	$42.50	7.553%	$45.71	$45.71	$45.70	$45.70
Purchase #3	$53.98	5.218%	$56.7967	$56.80	$56.80	$56.80
Purchase #4	$203.49	7.476%	$218.7029	$218.70	$218.70	$218.70
Purchase #5	$145.82	3.255%	$150.5664	$150.57	$150.55	$150.60
Purchase #6	$234.88	6.422%	$249.964	$249.96	$249.95	$250.00
Purchase #7	$171.91	5.578%	$181.4991	$181.50	$181.50	$181.50
7 purchase totals =	$971.48		$1,034.4131	$1,034.41	$1,034.35	$1,034.50