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	$148.43	9.410%	$162.3973	$162.40	$162.40	$162.40
Purchase #2	$11.30	13.503%	$12.8258	$12.83	$12.85	$12.80
Purchase #3	$177.73	3.569%	$184.0732	$184.07	$184.05	$184.10
Purchase #4	$183.48	11.352%	$204.3086	$204.31	$204.30	$204.30
Purchase #5	$119.31	6.138%	$126.6332	$126.63	$126.65	$126.60
Purchase #6	$206.51	4.793%	$216.408	$216.41	$216.40	$216.40
Purchase #7	$185.80	5.767%	$196.5151	$196.52	$196.50	$196.50
7 purchase totals =	$1,032.56		$1,103.1612	$1,103.17	$1,103.15	$1,103.10