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	$147.36	3.794%	$152.9508	$152.95	$152.95	$153.00
Purchase #2	$180.85	3.296%	$186.8108	$186.81	$186.80	$186.80
Purchase #3	$96.69	3.174%	$99.7589	$99.76	$99.75	$99.80
Purchase #4	$92.26	8.743%	$100.3263	$100.33	$100.35	$100.30
Purchase #5	$129.41	10.357%	$142.813	$142.81	$142.80	$142.80
Purchase #6	$202.56	3.699%	$210.0527	$210.05	$210.05	$210.10
Purchase #7	$36.47	10.646%	$40.3526	$40.35	$40.35	$40.40
7 purchase totals =	$885.60		$933.0651	$933.06	$933.05	$933.20