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	$107.58	9.328%	$117.6151	$117.62	$117.60	$117.60
Purchase #2	$50.28	13.686%	$57.1613	$57.16	$57.15	$57.20
Purchase #3	$201.79	6.564%	$215.0355	$215.04	$215.05	$215.00
Purchase #4	$182.77	7.261%	$196.0409	$196.04	$196.05	$196.00
Purchase #5	$181.79	5.132%	$191.1195	$191.12	$191.10	$191.10
Purchase #6	$50.73	3.156%	$52.331	$52.33	$52.35	$52.30
Purchase #7	$162.50	13.870%	$185.0388	$185.04	$185.05	$185.00
7 purchase totals =	$937.44		$1,014.3421	$1,014.35	$1,014.35	$1,014.20