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	$188.58	4.292%	$196.6739	$196.67	$196.65	$196.70
Purchase #2	$11.96	7.165%	$12.8169	$12.82	$12.80	$12.80
Purchase #3	$152.41	4.853%	$159.8065	$159.81	$159.80	$159.80
Purchase #4	$105.50	8.314%	$114.2713	$114.27	$114.25	$114.30
Purchase #5	$48.81	13.292%	$55.2978	$55.30	$55.30	$55.30
Purchase #6	$206.58	4.814%	$216.5248	$216.52	$216.50	$216.50
Purchase #7	$196.95	11.801%	$220.1921	$220.19	$220.20	$220.20
7 purchase totals =	$910.79		$975.5833	$975.58	$975.50	$975.60