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	$183.73	9.664%	$201.4857	$201.49	$201.50	$201.50
Purchase #2	$166.72	9.771%	$183.0102	$183.01	$183.00	$183.00
Purchase #3	$232.47	9.382%	$254.2803	$254.28	$254.30	$254.30
Purchase #4	$101.94	9.420%	$111.5427	$111.54	$111.55	$111.50
Purchase #5	$25.79	13.717%	$29.3276	$29.33	$29.35	$29.30
Purchase #6	$92.85	7.386%	$99.7079	$99.71	$99.70	$99.70
Purchase #7	$122.42	13.457%	$138.8941	$138.89	$138.90	$138.90
7 purchase totals =	$925.92		$1,018.2485	$1,018.25	$1,018.30	$1,018.20