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	$168.71	3.711%	$174.9708	$174.97	$174.95	$175.00
Purchase #2	$151.41	9.334%	$165.5426	$165.54	$165.55	$165.50
Purchase #3	$127.69	11.441%	$142.299	$142.30	$142.30	$142.30
Purchase #4	$157.33	10.327%	$173.5775	$173.58	$173.60	$173.60
Purchase #5	$95.91	9.439%	$104.9629	$104.96	$104.95	$105.00
Purchase #6	$241.41	12.700%	$272.0691	$272.07	$272.05	$272.10
Purchase #7	$24.39	10.749%	$27.0117	$27.01	$27.00	$27.00
7 purchase totals =	$966.85		$1,060.4336	$1,060.43	$1,060.40	$1,060.50