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	$98.55	7.313%	$105.757	$105.76	$105.75	$105.80
Purchase #2	$206.35	8.362%	$223.605	$223.61	$223.60	$223.60
Purchase #3	$176.76	3.328%	$182.6426	$182.64	$182.65	$182.60
Purchase #4	$202.33	13.484%	$229.6122	$229.61	$229.60	$229.60
Purchase #5	$89.69	3.107%	$92.4767	$92.48	$92.50	$92.50
Purchase #6	$18.68	13.344%	$21.1727	$21.17	$21.15	$21.20
Purchase #7	$147.33	3.623%	$152.6678	$152.67	$152.65	$152.70
7 purchase totals =	$939.69		$1,007.9340	$1,007.94	$1,007.90	$1,008.00