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	$210.81	6.762%	$225.065	$225.07	$225.05	$225.10
Purchase #2	$37.93	11.536%	$42.3056	$42.31	$42.30	$42.30
Purchase #3	$20.41	10.298%	$22.5118	$22.51	$22.50	$22.50
Purchase #4	$164.42	8.538%	$178.4582	$178.46	$178.45	$178.50
Purchase #5	$237.64	3.407%	$245.7364	$245.74	$245.75	$245.70
Purchase #6	$230.82	8.540%	$250.532	$250.53	$250.55	$250.50
Purchase #7	$209.48	10.676%	$231.8441	$231.84	$231.85	$231.80
7 purchase totals =	$1,111.51		$1,196.4531	$1,196.46	$1,196.45	$1,196.40