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	$58.89	7.600%	$63.3656	$63.37	$63.35	$63.40
Purchase #2	$56.99	11.839%	$63.737	$63.74	$63.75	$63.70
Purchase #3	$230.56	5.614%	$243.5036	$243.50	$243.50	$243.50
Purchase #4	$76.90	7.266%	$82.4876	$82.49	$82.50	$82.50
Purchase #5	$224.46	11.569%	$250.4278	$250.43	$250.45	$250.40
Purchase #6	$133.38	5.221%	$140.3438	$140.34	$140.35	$140.30
Purchase #7	$183.40	9.229%	$200.326	$200.33	$200.35	$200.30
7 purchase totals =	$964.58		$1,044.1914	$1,044.20	$1,044.25	$1,044.10