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	$215.72	6.873%	$230.5464	$230.55	$230.55	$230.50
Purchase #2	$238.44	10.551%	$263.5978	$263.60	$263.60	$263.60
Purchase #3	$180.53	10.557%	$199.5886	$199.59	$199.60	$199.60
Purchase #4	$113.74	10.243%	$125.3904	$125.39	$125.40	$125.40
Purchase #5	$164.30	5.221%	$172.8781	$172.88	$172.90	$172.90
Purchase #6	$111.39	6.581%	$118.7206	$118.72	$118.70	$118.70
Purchase #7	$137.33	10.612%	$151.9035	$151.90	$151.90	$151.90
7 purchase totals =	$1,161.45		$1,262.6254	$1,262.63	$1,262.65	$1,262.60