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	$196.78	13.760%	$223.8569	$223.86	$223.85	$223.90
Purchase #2	$88.60	7.704%	$95.4257	$95.43	$95.45	$95.40
Purchase #3	$167.58	8.660%	$182.0924	$182.09	$182.10	$182.10
Purchase #4	$93.43	7.755%	$100.6755	$100.68	$100.70	$100.70
Purchase #5	$211.29	9.409%	$231.1703	$231.17	$231.15	$231.20
Purchase #6	$170.33	4.197%	$177.4788	$177.48	$177.50	$177.50
Purchase #7	$227.31	7.278%	$243.8536	$243.85	$243.85	$243.90
7 purchase totals =	$1,155.32		$1,254.5532	$1,254.56	$1,254.60	$1,254.70