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	$216.71	7.567%	$233.1084	$233.11	$233.10	$233.10
Purchase #2	$184.91	6.261%	$196.4872	$196.49	$196.50	$196.50
Purchase #3	$93.47	5.361%	$98.4809	$98.48	$98.50	$98.50
Purchase #4	$33.77	9.593%	$37.0096	$37.01	$37.00	$37.00
Purchase #5	$65.51	6.248%	$69.6031	$69.60	$69.60	$69.60
Purchase #6	$232.73	5.258%	$244.9669	$244.97	$244.95	$245.00
Purchase #7	$136.69	11.266%	$152.0895	$152.09	$152.10	$152.10
7 purchase totals =	$963.79		$1,031.7456	$1,031.75	$1,031.75	$1,031.80