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	$174.26	5.276%	$183.454	$183.45	$183.45	$183.50
Purchase #2	$219.81	3.453%	$227.4	$227.40	$227.40	$227.40
Purchase #3	$120.82	7.485%	$129.8634	$129.86	$129.85	$129.90
Purchase #4	$162.32	3.464%	$167.9428	$167.94	$167.95	$167.90
Purchase #5	$91.59	11.210%	$101.8572	$101.86	$101.85	$101.90
Purchase #6	$119.85	6.742%	$127.9303	$127.93	$127.95	$127.90
Purchase #7	$172.53	3.777%	$179.0465	$179.05	$179.05	$179.00
7 purchase totals =	$1,061.18		$1,117.4942	$1,117.49	$1,117.50	$1,117.50