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	$110.91	7.573%	$119.3092	$119.31	$119.30	$119.30
Purchase #2	$151.89	7.200%	$162.8261	$162.83	$162.85	$162.80
Purchase #3	$19.99	9.498%	$21.8887	$21.89	$21.90	$21.90
Purchase #4	$88.49	9.353%	$96.7665	$96.77	$96.75	$96.80
Purchase #5	$203.34	7.693%	$218.9829	$218.98	$219.00	$219.00
Purchase #6	$144.83	8.137%	$156.6148	$156.61	$156.60	$156.60
Purchase #7	$229.67	8.611%	$249.4469	$249.45	$249.45	$249.40
7 purchase totals =	$949.12		$1,025.8351	$1,025.84	$1,025.85	$1,025.80