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	$163.28	13.808%	$185.8257	$185.83	$185.85	$185.80
Purchase #2	$214.76	13.529%	$243.8149	$243.81	$243.80	$243.80
Purchase #3	$69.84	12.552%	$78.6063	$78.61	$78.60	$78.60
Purchase #4	$140.50	4.258%	$146.4825	$146.48	$146.50	$146.50
Purchase #5	$154.59	4.794%	$162.001	$162.00	$162.00	$162.00
Purchase #6	$26.55	13.530%	$30.1422	$30.14	$30.15	$30.10
Purchase #7	$181.40	13.723%	$206.2935	$206.29	$206.30	$206.30
7 purchase totals =	$950.92		$1,053.1661	$1,053.16	$1,053.20	$1,053.10