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	$73.76	11.767%	$82.4393	$82.44	$82.45	$82.40
Purchase #2	$247.70	11.721%	$276.7329	$276.73	$276.75	$276.70
Purchase #3	$12.60	13.762%	$14.334	$14.33	$14.35	$14.30
Purchase #4	$223.64	7.544%	$240.5114	$240.51	$240.50	$240.50
Purchase #5	$196.87	13.417%	$223.284	$223.28	$223.30	$223.30
Purchase #6	$47.32	4.634%	$49.5128	$49.51	$49.50	$49.50
Purchase #7	$188.53	9.697%	$206.8118	$206.81	$206.80	$206.80
7 purchase totals =	$990.42		$1,093.6262	$1,093.61	$1,093.65	$1,093.50