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	$245.79	8.690%	$267.1492	$267.15	$267.15	$267.10
Purchase #2	$10.26	13.132%	$11.6073	$11.61	$11.60	$11.60
Purchase #3	$177.98	4.285%	$185.6064	$185.61	$185.60	$185.60
Purchase #4	$54.40	5.434%	$57.3561	$57.36	$57.35	$57.40
Purchase #5	$165.48	13.204%	$187.33	$187.33	$187.35	$187.30
Purchase #6	$180.46	6.267%	$191.7694	$191.77	$191.75	$191.80
Purchase #7	$219.30	13.337%	$248.548	$248.55	$248.55	$248.50
7 purchase totals =	$1,053.67		$1,149.3664	$1,149.38	$1,149.35	$1,149.30