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	$88.68	7.282%	$95.1377	$95.14	$95.15	$95.10
Purchase #2	$51.69	6.129%	$54.8581	$54.86	$54.85	$54.90
Purchase #3	$90.90	4.632%	$95.1105	$95.11	$95.10	$95.10
Purchase #4	$126.90	3.680%	$131.5699	$131.57	$131.55	$131.60
Purchase #5	$22.50	11.331%	$25.0495	$25.05	$25.05	$25.00
Purchase #6	$209.33	7.730%	$225.5112	$225.51	$225.50	$225.50
Purchase #7	$98.89	5.632%	$104.4595	$104.46	$104.45	$104.50
7 purchase totals =	$688.89		$731.6964	$731.70	$731.65	$731.70