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	$174.37	4.784%	$182.7119	$182.71	$182.70	$182.70
Purchase #2	$237.78	10.274%	$262.2095	$262.21	$262.20	$262.20
Purchase #3	$237.88	11.510%	$265.26	$265.26	$265.25	$265.30
Purchase #4	$113.87	11.728%	$127.2247	$127.22	$127.20	$127.20
Purchase #5	$6.76	7.520%	$7.2684	$7.27	$7.25	$7.30
Purchase #6	$9.61	9.140%	$10.4884	$10.49	$10.50	$10.50
Purchase #7	$160.83	11.585%	$179.4622	$179.46	$179.45	$179.50
7 purchase totals =	$941.10		$1,034.6251	$1,034.62	$1,034.55	$1,034.70