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	$228.63	3.163%	$235.8616	$235.86	$235.85	$235.90
Purchase #2	$158.50	4.604%	$165.7973	$165.80	$165.80	$165.80
Purchase #3	$192.65	13.619%	$218.887	$218.89	$218.90	$218.90
Purchase #4	$112.56	13.644%	$127.9177	$127.92	$127.90	$127.90
Purchase #5	$100.31	13.517%	$113.8689	$113.87	$113.85	$113.90
Purchase #6	$130.32	11.812%	$145.7134	$145.71	$145.70	$145.70
Purchase #7	$201.25	9.134%	$219.6322	$219.63	$219.65	$219.60
7 purchase totals =	$1,124.22		$1,227.6781	$1,227.68	$1,227.65	$1,227.70