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	$9.52	12.532%	$10.713	$10.71	$10.70	$10.70
Purchase #2	$150.86	12.558%	$169.805	$169.81	$169.80	$169.80
Purchase #3	$240.90	3.159%	$248.51	$248.51	$248.50	$248.50
Purchase #4	$182.51	7.222%	$195.6909	$195.69	$195.70	$195.70
Purchase #5	$119.67	6.172%	$127.056	$127.06	$127.05	$127.10
Purchase #6	$67.90	12.259%	$76.2239	$76.22	$76.20	$76.20
Purchase #7	$247.95	7.651%	$266.9207	$266.92	$266.90	$266.90
7 purchase totals =	$1,019.31		$1,094.9195	$1,094.92	$1,094.85	$1,094.90