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	$187.30	12.624%	$210.9448	$210.94	$210.95	$210.90
Purchase #2	$231.70	4.740%	$242.6826	$242.68	$242.70	$242.70
Purchase #3	$152.45	8.148%	$164.8716	$164.87	$164.85	$164.90
Purchase #4	$91.57	13.315%	$103.7625	$103.76	$103.75	$103.80
Purchase #5	$41.40	10.160%	$45.6062	$45.61	$45.60	$45.60
Purchase #6	$26.60	3.345%	$27.4898	$27.49	$27.50	$27.50
Purchase #7	$218.83	5.234%	$230.2836	$230.28	$230.30	$230.30
7 purchase totals =	$949.85		$1,025.6411	$1,025.63	$1,025.65	$1,025.70