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	$67.25	7.552%	$72.3287	$72.33	$72.35	$72.30
Purchase #2	$175.82	13.412%	$199.401	$199.40	$199.40	$199.40
Purchase #3	$209.64	6.628%	$223.5349	$223.53	$223.55	$223.50
Purchase #4	$33.64	6.726%	$35.9026	$35.90	$35.90	$35.90
Purchase #5	$192.96	10.586%	$213.3867	$213.39	$213.40	$213.40
Purchase #6	$171.26	3.490%	$177.237	$177.24	$177.25	$177.20
Purchase #7	$10.93	3.814%	$11.3469	$11.35	$11.35	$11.30
7 purchase totals =	$861.50		$933.1378	$933.14	$933.20	$933.00