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	$161.28	12.540%	$181.5045	$181.50	$181.50	$181.50
Purchase #2	$127.76	12.865%	$144.1963	$144.20	$144.20	$144.20
Purchase #3	$84.93	12.129%	$95.2312	$95.23	$95.25	$95.20
Purchase #4	$233.89	9.591%	$256.3224	$256.32	$256.30	$256.30
Purchase #5	$250.41	13.775%	$284.904	$284.90	$284.90	$284.90
Purchase #6	$57.35	5.776%	$60.6625	$60.66	$60.65	$60.70
Purchase #7	$146.25	11.365%	$162.8713	$162.87	$162.85	$162.90
7 purchase totals =	$1,061.87		$1,185.6922	$1,185.68	$1,185.65	$1,185.70