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	$203.25	4.746%	$212.8962	$212.90	$212.90	$212.90
Purchase #2	$90.80	8.479%	$98.4989	$98.50	$98.50	$98.50
Purchase #3	$158.90	6.679%	$169.5129	$169.51	$169.50	$169.50
Purchase #4	$92.58	7.548%	$99.5679	$99.57	$99.55	$99.60
Purchase #5	$197.90	4.808%	$207.415	$207.42	$207.40	$207.40
Purchase #6	$157.47	4.401%	$164.4003	$164.40	$164.40	$164.40
Purchase #7	$196.82	6.756%	$210.1172	$210.12	$210.10	$210.10
7 purchase totals =	$1,097.72		$1,162.4084	$1,162.42	$1,162.35	$1,162.40