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	$178.33	10.386%	$196.8514	$196.85	$196.85	$196.90
Purchase #2	$24.74	6.129%	$26.2563	$26.26	$26.25	$26.30
Purchase #3	$45.38	11.468%	$50.5842	$50.58	$50.60	$50.60
Purchase #4	$53.50	11.362%	$59.5787	$59.58	$59.60	$59.60
Purchase #5	$93.55	8.350%	$101.3614	$101.36	$101.35	$101.40
Purchase #6	$208.27	6.824%	$222.4823	$222.48	$222.50	$222.50
Purchase #7	$239.69	7.287%	$257.1562	$257.16	$257.15	$257.20
7 purchase totals =	$843.46		$914.2705	$914.27	$914.30	$914.50