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	$92.92	13.654%	$105.6073	$105.61	$105.60	$105.60
Purchase #2	$141.61	13.645%	$160.9327	$160.93	$160.95	$160.90
Purchase #3	$126.31	4.470%	$131.9561	$131.96	$131.95	$132.00
Purchase #4	$188.52	4.776%	$197.5237	$197.52	$197.50	$197.50
Purchase #5	$41.68	4.532%	$43.5689	$43.57	$43.55	$43.60
Purchase #6	$103.33	11.212%	$114.9154	$114.92	$114.90	$114.90
Purchase #7	$242.84	8.578%	$263.6708	$263.67	$263.65	$263.70
7 purchase totals =	$937.21		$1,018.1749	$1,018.18	$1,018.10	$1,018.20