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	$35.95	3.230%	$37.1112	$37.11	$37.10	$37.10
Purchase #2	$225.41	4.757%	$236.1328	$236.13	$236.15	$236.10
Purchase #3	$168.50	3.458%	$174.3267	$174.33	$174.35	$174.30
Purchase #4	$245.65	8.512%	$266.5597	$266.56	$266.55	$266.60
Purchase #5	$186.74	9.531%	$204.5382	$204.54	$204.55	$204.50
Purchase #6	$67.88	5.874%	$71.8673	$71.87	$71.85	$71.90
Purchase #7	$86.94	9.756%	$95.4219	$95.42	$95.40	$95.40
7 purchase totals =	$1,017.07		$1,085.9578	$1,085.96	$1,085.95	$1,085.90