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	$189.81	3.410%	$196.2825	$196.28	$196.30	$196.30
Purchase #2	$106.79	5.317%	$112.468	$112.47	$112.45	$112.50
Purchase #3	$106.87	12.565%	$120.2982	$120.30	$120.30	$120.30
Purchase #4	$186.30	5.273%	$196.1236	$196.12	$196.10	$196.10
Purchase #5	$54.25	11.426%	$60.4486	$60.45	$60.45	$60.40
Purchase #6	$144.31	5.662%	$152.4808	$152.48	$152.50	$152.50
Purchase #7	$184.37	5.870%	$195.1925	$195.19	$195.20	$195.20
7 purchase totals =	$972.70		$1,033.2942	$1,033.29	$1,033.30	$1,033.30