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	$145.94	4.626%	$152.6912	$152.69	$152.70	$152.70
Purchase #2	$175.27	3.535%	$181.4658	$181.47	$181.45	$181.50
Purchase #3	$84.79	4.543%	$88.642	$88.64	$88.65	$88.60
Purchase #4	$247.40	6.113%	$262.5236	$262.52	$262.50	$262.50
Purchase #5	$74.99	13.510%	$85.1211	$85.12	$85.10	$85.10
Purchase #6	$162.63	12.106%	$182.318	$182.32	$182.30	$182.30
Purchase #7	$212.41	4.815%	$222.6375	$222.64	$222.65	$222.60
7 purchase totals =	$1,103.43		$1,175.3992	$1,175.40	$1,175.35	$1,175.30