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	$88.55	8.550%	$96.121	$96.12	$96.10	$96.10
Purchase #2	$189.57	11.122%	$210.654	$210.65	$210.65	$210.70
Purchase #3	$44.29	3.298%	$45.7507	$45.75	$45.75	$45.80
Purchase #4	$203.25	9.289%	$222.1299	$222.13	$222.15	$222.10
Purchase #5	$73.63	13.320%	$83.4375	$83.44	$83.45	$83.40
Purchase #6	$63.66	5.494%	$67.1575	$67.16	$67.15	$67.20
Purchase #7	$151.63	13.501%	$172.1016	$172.10	$172.10	$172.10
7 purchase totals =	$814.58		$897.3522	$897.35	$897.35	$897.40