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	$174.57	9.741%	$191.5749	$191.57	$191.55	$191.60
Purchase #2	$214.64	4.108%	$223.4574	$223.46	$223.45	$223.50
Purchase #3	$160.60	13.796%	$182.7564	$182.76	$182.75	$182.80
Purchase #4	$20.82	7.465%	$22.3742	$22.37	$22.35	$22.40
Purchase #5	$205.30	3.721%	$212.9392	$212.94	$212.95	$212.90
Purchase #6	$119.39	9.327%	$130.5255	$130.53	$130.55	$130.50
Purchase #7	$109.54	9.794%	$120.2683	$120.27	$120.25	$120.30
7 purchase totals =	$1,004.86		$1,083.8959	$1,083.90	$1,083.85	$1,084.00