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	$175.36	3.139%	$180.8646	$180.86	$180.85	$180.90
Purchase #2	$100.63	5.213%	$105.8758	$105.88	$105.90	$105.90
Purchase #3	$196.50	5.796%	$207.8891	$207.89	$207.90	$207.90
Purchase #4	$29.70	8.111%	$32.109	$32.11	$32.10	$32.10
Purchase #5	$146.74	3.289%	$151.5663	$151.57	$151.55	$151.60
Purchase #6	$219.30	5.751%	$231.9119	$231.91	$231.90	$231.90
Purchase #7	$179.35	3.424%	$185.4909	$185.49	$185.50	$185.50
7 purchase totals =	$1,047.58		$1,095.7076	$1,095.71	$1,095.70	$1,095.80