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	$212.51	7.525%	$228.5014	$228.50	$228.50	$228.50
Purchase #2	$70.33	4.178%	$73.2684	$73.27	$73.25	$73.30
Purchase #3	$105.40	5.526%	$111.2244	$111.22	$111.20	$111.20
Purchase #4	$161.41	8.252%	$174.7296	$174.73	$174.75	$174.70
Purchase #5	$105.48	3.663%	$109.3437	$109.34	$109.35	$109.30
Purchase #6	$169.89	8.606%	$184.5107	$184.51	$184.50	$184.50
Purchase #7	$208.57	9.409%	$228.1944	$228.19	$228.20	$228.20
7 purchase totals =	$1,033.59		$1,109.7726	$1,109.76	$1,109.75	$1,109.70