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	$216.58	9.370%	$236.8735	$236.87	$236.85	$236.90
Purchase #2	$69.42	4.458%	$72.5147	$72.51	$72.50	$72.50
Purchase #3	$79.89	4.663%	$83.6153	$83.62	$83.60	$83.60
Purchase #4	$26.56	3.143%	$27.3948	$27.39	$27.40	$27.40
Purchase #5	$149.38	6.807%	$159.5483	$159.55	$159.55	$159.50
Purchase #6	$182.65	5.322%	$192.3706	$192.37	$192.35	$192.40
Purchase #7	$220.33	12.713%	$248.3406	$248.34	$248.35	$248.30
7 purchase totals =	$944.81		$1,020.6578	$1,020.65	$1,020.60	$1,020.60