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	$210.93	8.119%	$228.0554	$228.06	$228.05	$228.10
Purchase #2	$121.58	7.380%	$130.5526	$130.55	$130.55	$130.60
Purchase #3	$93.31	7.443%	$100.2551	$100.26	$100.25	$100.30
Purchase #4	$12.53	9.406%	$13.7086	$13.71	$13.70	$13.70
Purchase #5	$84.64	9.158%	$92.3913	$92.39	$92.40	$92.40
Purchase #6	$196.31	12.847%	$221.5299	$221.53	$221.55	$221.50
Purchase #7	$222.75	12.510%	$250.616	$250.62	$250.60	$250.60
7 purchase totals =	$942.05		$1,037.1089	$1,037.12	$1,037.10	$1,037.20