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	$216.96	8.700%	$235.8355	$235.84	$235.85	$235.80
Purchase #2	$29.94	13.329%	$33.9307	$33.93	$33.95	$33.90
Purchase #3	$38.97	11.140%	$43.3113	$43.31	$43.30	$43.30
Purchase #4	$152.95	12.807%	$172.5383	$172.54	$172.55	$172.50
Purchase #5	$146.53	12.711%	$165.1554	$165.16	$165.15	$165.20
Purchase #6	$179.27	4.148%	$186.7061	$186.71	$186.70	$186.70
Purchase #7	$210.26	8.487%	$228.1048	$228.10	$228.10	$228.10
7 purchase totals =	$974.88		$1,065.5821	$1,065.59	$1,065.60	$1,065.50