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	$194.31	5.624%	$205.238	$205.24	$205.25	$205.20
Purchase #2	$65.49	4.568%	$68.4816	$68.48	$68.50	$68.50
Purchase #3	$54.37	9.679%	$59.6325	$59.63	$59.65	$59.60
Purchase #4	$211.29	4.461%	$220.7156	$220.72	$220.70	$220.70
Purchase #5	$194.56	3.142%	$200.6731	$200.67	$200.65	$200.70
Purchase #6	$53.76	10.355%	$59.3268	$59.33	$59.35	$59.30
Purchase #7	$174.80	13.225%	$197.9173	$197.92	$197.90	$197.90
7 purchase totals =	$948.58		$1,011.9849	$1,011.99	$1,012.00	$1,011.90