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	$87.46	5.676%	$92.4242	$92.42	$92.40	$92.40
Purchase #2	$106.64	7.288%	$114.4119	$114.41	$114.40	$114.40
Purchase #3	$90.66	5.120%	$95.3018	$95.30	$95.30	$95.30
Purchase #4	$147.70	4.742%	$154.7039	$154.70	$154.70	$154.70
Purchase #5	$89.56	11.519%	$99.8764	$99.88	$99.90	$99.90
Purchase #6	$43.34	6.724%	$46.2542	$46.25	$46.25	$46.30
Purchase #7	$145.95	4.518%	$152.544	$152.54	$152.55	$152.50
7 purchase totals =	$711.31		$755.5164	$755.50	$755.50	$755.50