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	$187.72	4.363%	$195.9102	$195.91	$195.90	$195.90
Purchase #2	$151.33	13.393%	$171.5976	$171.60	$171.60	$171.60
Purchase #3	$165.69	9.517%	$181.4587	$181.46	$181.45	$181.50
Purchase #4	$88.54	9.292%	$96.7671	$96.77	$96.75	$96.80
Purchase #5	$53.73	11.222%	$59.7596	$59.76	$59.75	$59.80
Purchase #6	$93.99	9.481%	$102.9012	$102.90	$102.90	$102.90
Purchase #7	$142.42	11.390%	$158.6416	$158.64	$158.65	$158.60
7 purchase totals =	$883.42		$967.0360	$967.04	$967.00	$967.10