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	$147.53	9.834%	$162.0381	$162.04	$162.05	$162.00
Purchase #2	$138.91	11.813%	$155.3194	$155.32	$155.30	$155.30
Purchase #3	$199.32	11.224%	$221.6917	$221.69	$221.70	$221.70
Purchase #4	$90.85	6.539%	$96.7907	$96.79	$96.80	$96.80
Purchase #5	$157.51	9.255%	$172.0876	$172.09	$172.10	$172.10
Purchase #6	$136.36	6.534%	$145.2698	$145.27	$145.25	$145.30
Purchase #7	$79.64	3.315%	$82.2801	$82.28	$82.30	$82.30
7 purchase totals =	$950.12		$1,035.4774	$1,035.48	$1,035.50	$1,035.50