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	$33.96	11.440%	$37.845	$37.85	$37.85	$37.80
Purchase #2	$233.30	13.115%	$263.8973	$263.90	$263.90	$263.90
Purchase #3	$121.49	4.702%	$127.2025	$127.20	$127.20	$127.20
Purchase #4	$118.88	10.688%	$131.5859	$131.59	$131.60	$131.60
Purchase #5	$140.66	8.514%	$152.6358	$152.64	$152.65	$152.60
Purchase #6	$119.29	5.416%	$125.7507	$125.75	$125.75	$125.80
Purchase #7	$209.81	9.179%	$229.0685	$229.07	$229.05	$229.10
7 purchase totals =	$977.39		$1,067.9857	$1,068.00	$1,068.00	$1,068.00