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	$208.74	4.461%	$218.0519	$218.05	$218.05	$218.10
Purchase #2	$222.44	11.645%	$248.3431	$248.34	$248.35	$248.30
Purchase #3	$38.50	3.304%	$39.772	$39.77	$39.75	$39.80
Purchase #4	$243.55	6.455%	$259.2712	$259.27	$259.25	$259.30
Purchase #5	$57.52	8.768%	$62.5634	$62.56	$62.55	$62.60
Purchase #6	$20.31	5.554%	$21.438	$21.44	$21.45	$21.40
Purchase #7	$151.39	13.169%	$171.3265	$171.33	$171.35	$171.30
7 purchase totals =	$942.45		$1,020.7661	$1,020.76	$1,020.75	$1,020.80