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	$219.98	7.160%	$235.7306	$235.73	$235.75	$235.70
Purchase #2	$80.40	11.444%	$89.601	$89.60	$89.60	$89.60
Purchase #3	$48.39	13.525%	$54.9347	$54.93	$54.95	$54.90
Purchase #4	$74.25	6.251%	$78.8914	$78.89	$78.90	$78.90
Purchase #5	$92.84	6.485%	$98.8607	$98.86	$98.85	$98.90
Purchase #6	$154.39	7.309%	$165.6744	$165.67	$165.65	$165.70
Purchase #7	$141.27	7.786%	$152.2693	$152.27	$152.25	$152.30
7 purchase totals =	$811.52		$875.9621	$875.95	$875.95	$876.00