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	$158.37	4.518%	$165.5252	$165.53	$165.55	$165.50
Purchase #2	$184.35	3.363%	$190.5497	$190.55	$190.55	$190.50
Purchase #3	$75.58	3.748%	$78.4127	$78.41	$78.40	$78.40
Purchase #4	$97.95	3.388%	$101.2685	$101.27	$101.25	$101.30
Purchase #5	$214.91	6.629%	$229.1564	$229.16	$229.15	$229.20
Purchase #6	$197.93	6.171%	$210.1443	$210.14	$210.15	$210.10
Purchase #7	$131.25	8.173%	$141.9771	$141.98	$142.00	$142.00
7 purchase totals =	$1,060.34		$1,117.0339	$1,117.04	$1,117.05	$1,117.00