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	$195.97	13.572%	$222.567	$222.57	$222.55	$222.60
Purchase #2	$18.59	6.222%	$19.7467	$19.75	$19.75	$19.70
Purchase #3	$37.56	7.291%	$40.2985	$40.30	$40.30	$40.30
Purchase #4	$88.86	11.758%	$99.3082	$99.31	$99.30	$99.30
Purchase #5	$194.50	11.450%	$216.7703	$216.77	$216.75	$216.80
Purchase #6	$216.61	5.769%	$229.1062	$229.11	$229.10	$229.10
Purchase #7	$92.89	5.634%	$98.1234	$98.12	$98.10	$98.10
7 purchase totals =	$844.98		$925.9203	$925.93	$925.85	$925.90