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	$196.31	8.777%	$213.5401	$213.54	$213.55	$213.50
Purchase #2	$218.97	13.776%	$249.1353	$249.14	$249.15	$249.10
Purchase #3	$75.96	12.389%	$85.3707	$85.37	$85.35	$85.40
Purchase #4	$70.45	3.204%	$72.7072	$72.71	$72.70	$72.70
Purchase #5	$222.50	3.169%	$229.551	$229.55	$229.55	$229.60
Purchase #6	$147.38	12.772%	$166.2034	$166.20	$166.20	$166.20
Purchase #7	$62.44	3.640%	$64.7128	$64.71	$64.70	$64.70
7 purchase totals =	$994.01		$1,081.2205	$1,081.22	$1,081.20	$1,081.20