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	$151.57	13.308%	$171.7409	$171.74	$171.75	$171.70
Purchase #2	$52.35	3.270%	$54.0618	$54.06	$54.05	$54.10
Purchase #3	$200.78	5.322%	$211.4655	$211.47	$211.45	$211.50
Purchase #4	$144.50	7.782%	$155.745	$155.75	$155.75	$155.70
Purchase #5	$133.36	12.674%	$150.262	$150.26	$150.25	$150.30
Purchase #6	$98.25	13.585%	$111.5973	$111.60	$111.60	$111.60
Purchase #7	$168.66	8.306%	$182.6689	$182.67	$182.65	$182.70
7 purchase totals =	$949.47		$1,037.5414	$1,037.55	$1,037.50	$1,037.60