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	$210.49	6.299%	$223.7488	$223.75	$223.75	$223.70
Purchase #2	$7.76	8.422%	$8.4135	$8.41	$8.40	$8.40
Purchase #3	$61.78	9.570%	$67.6923	$67.69	$67.70	$67.70
Purchase #4	$90.78	10.192%	$100.0323	$100.03	$100.05	$100.00
Purchase #5	$167.89	9.282%	$183.4735	$183.47	$183.45	$183.50
Purchase #6	$220.86	10.680%	$244.4478	$244.45	$244.45	$244.40
Purchase #7	$197.44	13.120%	$223.3441	$223.34	$223.35	$223.30
7 purchase totals =	$957.00		$1,051.1523	$1,051.14	$1,051.15	$1,051.00