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	$236.73	3.484%	$244.9777	$244.98	$245.00	$245.00
Purchase #2	$31.28	3.294%	$32.3104	$32.31	$32.30	$32.30
Purchase #3	$187.79	6.600%	$200.1841	$200.18	$200.20	$200.20
Purchase #4	$181.31	12.795%	$204.5086	$204.51	$204.50	$204.50
Purchase #5	$67.67	5.477%	$71.3763	$71.38	$71.40	$71.40
Purchase #6	$140.60	4.393%	$146.7766	$146.78	$146.80	$146.80
Purchase #7	$142.49	9.673%	$156.2731	$156.27	$156.25	$156.30
7 purchase totals =	$987.87		$1,056.4068	$1,056.41	$1,056.45	$1,056.50