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	$136.56	4.541%	$142.7612	$142.76	$142.75	$142.80
Purchase #2	$83.43	4.306%	$87.0225	$87.02	$87.00	$87.00
Purchase #3	$141.27	10.350%	$155.8914	$155.89	$155.90	$155.90
Purchase #4	$187.69	4.538%	$196.2074	$196.21	$196.20	$196.20
Purchase #5	$205.60	5.205%	$216.3015	$216.30	$216.30	$216.30
Purchase #6	$125.43	13.350%	$142.1749	$142.17	$142.15	$142.20
Purchase #7	$151.94	7.441%	$163.2459	$163.25	$163.25	$163.20
7 purchase totals =	$1,031.92		$1,103.6048	$1,103.60	$1,103.55	$1,103.60