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	$157.46	3.287%	$162.6357	$162.64	$162.65	$162.60
Purchase #2	$54.41	8.653%	$59.1181	$59.12	$59.10	$59.10
Purchase #3	$48.27	5.866%	$51.1015	$51.10	$51.10	$51.10
Purchase #4	$7.43	4.602%	$7.7719	$7.77	$7.75	$7.80
Purchase #5	$46.88	7.872%	$50.5704	$50.57	$50.55	$50.60
Purchase #6	$183.27	6.552%	$195.2779	$195.28	$195.30	$195.30
Purchase #7	$35.79	4.223%	$37.3014	$37.30	$37.30	$37.30
7 purchase totals =	$533.51		$563.7769	$563.78	$563.75	$563.80