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	$219.64	5.111%	$230.8658	$230.87	$230.85	$230.90
Purchase #2	$59.51	5.467%	$62.7634	$62.76	$62.75	$62.80
Purchase #3	$32.84	8.128%	$35.5092	$35.51	$35.50	$35.50
Purchase #4	$222.80	5.401%	$234.8334	$234.83	$234.85	$234.80
Purchase #5	$240.68	8.165%	$260.3315	$260.33	$260.35	$260.30
Purchase #6	$228.72	8.479%	$248.1132	$248.11	$248.10	$248.10
Purchase #7	$70.36	11.281%	$78.2973	$78.30	$78.30	$78.30
7 purchase totals =	$1,074.55		$1,150.7138	$1,150.71	$1,150.70	$1,150.70