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	$163.41	11.294%	$181.8655	$181.87	$181.85	$181.90
Purchase #2	$13.72	4.420%	$14.3264	$14.33	$14.35	$14.30
Purchase #3	$160.73	8.560%	$174.4885	$174.49	$174.50	$174.50
Purchase #4	$56.31	5.549%	$59.4346	$59.43	$59.45	$59.40
Purchase #5	$209.94	13.443%	$238.1622	$238.16	$238.15	$238.20
Purchase #6	$171.32	4.373%	$178.8118	$178.81	$178.80	$178.80
Purchase #7	$159.69	3.639%	$165.5011	$165.50	$165.50	$165.50
7 purchase totals =	$935.12		$1,012.5901	$1,012.59	$1,012.60	$1,012.60