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	$181.77	10.398%	$200.6704	$200.67	$200.65	$200.70
Purchase #2	$66.34	7.849%	$71.547	$71.55	$71.55	$71.50
Purchase #3	$185.51	3.676%	$192.3293	$192.33	$192.35	$192.30
Purchase #4	$184.79	5.699%	$195.3212	$195.32	$195.30	$195.30
Purchase #5	$219.65	12.732%	$247.6158	$247.62	$247.60	$247.60
Purchase #6	$181.86	3.472%	$188.1742	$188.17	$188.15	$188.20
Purchase #7	$56.94	5.307%	$59.9618	$59.96	$59.95	$60.00
7 purchase totals =	$1,076.86		$1,155.6197	$1,155.62	$1,155.55	$1,155.60