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	7.662%	$175.9305	$175.93	$175.95	$175.90
Purchase #2	$35.91	5.583%	$37.9149	$37.91	$37.90	$37.90
Purchase #3	$101.86	4.331%	$106.2716	$106.27	$106.25	$106.30
Purchase #4	$218.64	6.791%	$233.4878	$233.49	$233.50	$233.50
Purchase #5	$128.52	9.367%	$140.5585	$140.56	$140.55	$140.60
Purchase #6	$212.45	6.562%	$226.391	$226.39	$226.40	$226.40
Purchase #7	$80.76	11.855%	$90.3341	$90.33	$90.35	$90.30
7 purchase totals =	$941.55		$1,010.8884	$1,010.88	$1,010.90	$1,010.90